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WaterEurope
ZCAM, Zaragoza, Spain
June 12-14, 2014
Organizers!

!
!

Livia E.Bove (CNRS and Université Pierre et Marie Curie, Paris and EPFL, Lausanne)!
Giancarlo Franzese (Universitat de Barcelona, Barcelona)!
Jordi Marti (Universitat Politècnica de Catalunya-Barcelona Tech, Barcelona)

Sponsored by

!

Full information available at:!
http://www.cecam.org/workshop-1089.html!
http://www.z-cam.es/

!
!

Scope!

WaterEurope is a workshop that aims to provide an opportunity for theoretical and
experimental scientists from different branches of science to discuss the state of the art
in the field of water research and related areas: theory, experiments and computer
simulations on water, modeling and parameterization of force fields, study of water at
interfaces and near macromolecules, preview of future developments (polarizability
including higher multipolar effects, new potentials for water in biosystems and at
extreme conditions).!

International Advisory Scientific Committee!

!!
Livia E. Bove (CNRS and Université Pierre et Marie Curie, Paris and EPFL, Lausanne) !
Athena Coustenis (LESIA, Observatoire de Paris-Meudon, Paris)!
Giancarlo Franzese (Universitat de Barcelona, Barcelona)!
Elvira Guàrdia (Universitat Politècnica de Catalunya-Barcelona Tech, Barcelona)!
Gerhard Hummer (Max Planck Institute of Biophysics, Frankfurt am Main)!
Thomas Loerting (Innsbruck University, Innsbruck) !
Jordi Marti (Universitat Politècnica de Catalunya-Barcelona Tech, Barcelona)!
Marco Saitta (IMPMC, Université Pierre et Marie Curie, Paris)!
James Skinner (University of Wisconsin, Madison)

2

Contents
Program

3

Talks

5

Posters

55

Participants

78

3

PROGRAM
Thu  12
OPENING

Fri  13

Sat  14

8:00-­‐8:10  
8:10-­‐8:50
8:50-­‐9:05
9:05-­‐9:20
9:20-­‐9:35

RICCI
BERNABEI
CERVENY
COREZZI

PARRINELLO
MARTELLI
BRUNI
FRAXEDAS

TEIXEIRA
FOMIN
SUFFRITTI
MITSARI

9:35-­‐10:15

BARRIL  

FERNANDEZ-­‐SERRA

NETZ

10:15-­‐10:45 Coffee  30

Coffee  30

Coffee  30

10:45-­‐11:15
11:15-­‐11:30
11:30-­‐11:45
11:45-­‐12:00
12:00-­‐12:15

SAITTA
RUSSINA
LUDL
ULIVI
GONZALEZ-­‐SALGADO   GOMEZ-­‐ALVAREZ
SANZ
ZUBELTZU
SMIRNOV
QUIRKE
 (12:00-­‐12:40)
JUNGWIRTH
CLOSURE
 (12:40-­‐12:55)

CESARO
BITTNER
ALIOTTA
SCHIRÓ
BADASYAN

12:15-­‐12:55 CHAMPION  
12:55-­‐14:30 Lunch  1:35

Lunch  1:35

14:30-­‐15:10 BORGIS

BRESME

15:10-­‐15:50 VUILLEUMIER

CAUPIN

15:50-­‐16:30 KUHS

VEGA

16:30-­‐17:00 Coffee    30

Coffee  30

17:00-­‐17:30
17:30:17:45
17:45-­‐18:00
18:00-­‐18:15
18:15-­‐18:30

MOLINERO
RUSSO
AMMAN-­‐WINKEL
VERDAGUER  
GONZALEZ-­‐SILVEIRA

HAMM
MALLAMACE
CUPANE
BIANCO

18:30-­‐19:10 GALLO

19:10-­‐20:30
21.00

LYONNARD

WELCOME  PARTY  /  
POSTERS
Social  Dinner

4

Talks
Thursay 12th of June

Friday 13th of June

Saturday 14th of June

Ricci ∗
Bernabei
Cerveny
Corezzi
Barril ∗
Cesàro
Bittner
Aliotta
Schiró
Badasyan
Champion ∗

Parrinello ∗
Martelli
Bruni
Fraxedas
Fernández-Serra ∗
Saitta
Ludl
González-Salgado
Sanz
Smirnov
Jungwirth ∗

Teixeira ∗
Fomin
Suffritti
Mitsari
Netz ∗
Russina
Ulivi
Gómez-Alvarez
Zubeltzu
Quirke ∗

Borgis ∗
Vuilleumier ∗
Kuhs ∗
Hamm
Mallamace
Cupane
Bianco
Gallo ∗

Bresme ∗
Caupin ∗
Vega ∗
Molinero
Russo
Amman-Winkel
Verdaguer
González-Silveira
Lyonnard ∗

∗ : invited speakers

5

Water, glucose and trehalose: sweet or tasteless?
Maria Antonietta Ricci, Fabio Bruni and Laura Maugeri
Department of Science, Nanoscience Division, Università Roma Tre, via della Vasca Navale 84,
I-00146 Roma, Italy

The observation made by early naturalists that some organisms could tolerate extreme
environmental condisions and “enjoy the advantage of real resurrection after death” [1]
stimulated research, that still continues to this day, concerning the relative effectiveness and
efficiency of sugars as cryo- and drought-protectant. In particular, trehalose is much more
efficient than glucose and for this reason is produced by several organisms who have set up a
survival strategy against drought or extremely low temperatures. No clear and definitive
structural explanation for this evidence was put forward [2], except that this is not related to
the number or position of hydroxyl groups available for hydrogen bonding. About 20 years
ago, Green and Angell demonstrated [3] that the efficiency order ‘‘trehalose, lactose, maltose,
fructose, sucrose, glucose, … ’’ is exactly that of the glass transition temperatures and
suggested the protective efficiency is therefore function of the viscosity of the intracellular
medium.
The origin of the beneficial role of sugars, and specifically trehalose, should reside in the
mechanism of interaction with enzymes, and biomembranes which are preserved against
stressing conditions. Moreover it is clear that water should play an important role in
determining their physical and chemical stability.
In this talk we present a detailed neutron diffraction study of aqueous solutions of trehalose
and glucose, showing clear differences in the way the two sugars hydrate, possibly suggesting
why trehalose can be vetrified much easily than glucose.

[1] M. Spallanzani, Opuscules de Physique Animale et Vegetale (1776). Translated from
Italian by J. Senebier, Opuscules de Physique Animale et Vegetale 2, 203 (1787).
[2] G. Cottone, G. Ciccotti, L. Cordone, J. Chem. Phys. 117, 9862 (2002).
[3] J.L. Green, C.A. Angell, J. Chem. Phys. 93, 2880 (1989).

6

Molecular characterization of the hydration water of organic
and inorganic interfaces
Marco Bernabei†, Alfonso de Simone‡, Paul Martin§ , Eva-Valsami Jones§ and Giancarlo
Franzese†


Deparament de Fisica Fonamemtal, Universitat de Barcelona, Diagonal 645,
E-08028 Barcelona, Spain


§

Division of Molecular Bioscience, Imperial College, London, UK
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham,
UK

In the framework of a multiscale approach to study the protein-nanoparticle interaction in
solution, we study here how to include the effects of the interface on the hydration water of
nanoparticles (NP) and proteins featuring different hydropacy. From atomistic molecular
dynamic simulations of a single nanometer-size solute in water, we study the hydration
structure of Silver NP, hydrophobin (HFBI) and human serum albumin (HSA). We analyze
the energetics the structure, the diffusive and orientational dynamics of waters in the
hydration shell. We discuss the effects of inorganic and organic interfaces of different
hydropacy on the structure and persistence of the average tetrahedral hydrogen bond network
present in bulk.
.

7

Water dynamics in a genuine biological solution at supercooled temperatures
Silvina Cerveny†‡


Centro de Física de Materiales CFM/UPV-Materials Physics Centre MPC, Paseo Manuel de
Lardizabal5, 20018, San Sebastián, Spain


Donostia International Physics Centre, DIPC, 20018, San Sebastián, Spain
.

Studies of protein dynamics at low temperatures are only performed on hydrated
powders and not in biologically realistic solutions of water, due to water crystallization.
However, here we avoid the problem of crystallization by reducing the size of the
biomolecules. By choosing the single amino acid L-Lysine we have been able to perform a
dielectric relaxation study of its dynamics when it is fully dissolved in water, without having
any problem of crystallization at any temperature. The results suggest that the conformational
dynamics of the amino acid is determined by the viscosity related water dynamics, in a
similar way as previously observed for solvated proteins. This finding challenges the role of
complexity of proteins and also indicates that water may have a universal role for
biomolecular dynamics. In addition, we found that the water dynamics is unique for this kind
of system. In no other water containing system a viscosity related α-relaxation of water has
been observed at the same temperature as its more local β-relaxation is present.
The similar role of water for the dynamics of amino acids and proteins may have
important implications for both the general understanding water in biological systems as well
as the detailed nature of protein dynamics. A consequence of the present results is also that
the dynamics of peptides is expected to be determined by the water dynamics in a similar way
as here observed for lysine and previously established for proteins.

8

Hydration and Rotational Diffusion of Levoglucosan in Aqueous Solutions
Silvia Corezzi,† Paola Sassi,‡ Marco Paolantoni,‡ Lucia Comez,§ Assunta Morresi‡ and
Daniele Fioretto†*


Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli,
I-06123 Perugia, Italy

Dipartimento di Chimica, Università di Perugia, Via Elce di Sotto 8,
I-06123 Perugia, Italy
§
IOM-CNR c/o Dipartimento di Fisica e Geologia,Università di Perugia, Via Pascoli,
I-06123 Perugia, Italy
*
Centro di Eccellenza sui Materiali Innovativi Nanostruttuarati (CEMIN), Università di Perugia, Via
Elce di Sotto 8, I-06123 Perugia, Italy

Corresponding author: silvia.corezzi@fisica.unipg.it
Extended frequency range depolarized light scattering (EDLS) measurements of waterlevoglucosan (LG) solutions are reported at different concentrations and temperatures to
assess the effect of the presence and distribution of hydroxyl groups on the dynamics of
hydration water. The anhydro bridge, reducing from five to three the number of hydroxyl
groups with respect to glucose, considerably affects the hydration properties of LG with
respect to those revealed by EDLS in mono and disaccharides. In particular, the retardation
imposed by LG on the dynamics of the surrounding water molecules with respect to the bulk
water is ≈ 3-4, that is lower than ≈ 5-6 previously found in glucose, fructose, trehalose, and
sucrose. Conversely, the average number of water molecules dynamically perturbed by one
LG molecule is 24, almost double than that found in water-glucose mixtures. These results
suggest that the ability of sugar molecules to form H-bonds with the surrounding water
through hydroxyl groups, while it produces a more effective retardation also reduces
drastically the spatial extent of the perturbation on the H-bond network. In addition, the
concentration dependence of the hydration number reveals the aptitude of LG to produce
large aggregates in solution. The analysis of the shear viscosity and rotational diffusion time
suggests a very short lifetime for these aggregates, typically faster than ≈ 20 picoseconds.

9

Understanding the role of water molecules in the drug-target binding process:
Advances in structure-based drug discovery
Xavier Barril†


ICREA & Departament de Fisicoquímica, Universitat de Barcelona, Av. Joan XXII s/n,
E-08028 Barcelona, Spain

Water is ubiquitous in biological systems and it plays a dominant effect on all aspects of
molecular recognition in the biological environment, from protein folding and formation of
lipid bilayers to enzymatic processes, to name just a few. Drug discovery is mostly concerned
with understanding the formation of non-covalent complexes between the targeted biological
system (usually a protein) and a synthetic compound that will ultimately be developed into a
drug candidate. For practical reasons and lack of better tools, the effect of water has largely
been ignored, resulting in deficient predictive capacity of structure-based drug discovery
methods. However there has been substantial progress on this front in recent years.
In this talk I will give a brief overview of the effect of water in protein-ligand binding
processes and present two contributions of the group towards understanding and predicting
kinetic and thermodynamic effects that are largely mediated by water [1, 2].

Fig. 1: Hydration sites in the active site of Hsp90 (left) and their predicted affinity (right).
Blue diamonds correspond to binding affinities derived from MD simulations with water as
the sole solvent. Red squares include the affinity of organic solvents for the same sites,
showing that at some spots, water molecules are intrinsically stable but can be displaced
because other types of molecules bind even better.
[1] P. Schmidtke, F.J. Luque, J.B. Murray, X. Barril, J Am Chem Soc 133, 18903 (2011)
[2] D. Alvarez-Garcia, X. Barril, Submitted.

10

Biophysics of isothermal dehydration of thin films of biomaterials
A. Cesàroa,b, E. Guriana, B. Bellicha, E. Eliseia, A. Rampinoc, C. Schneiderc,
J. W. Bradyd, R. Heyde, M.-L. Saboungif
a

Laboratory of Physical and Macromolecular Chemistry, University of Trieste,
Via Giorgieri 1, I-34127 Trieste, Italy
b
Elettra Sincrotrone Trieste, Area Science Park, I-34149 Trieste, Italy
c
LN-CIB Trieste, Area Science Park, Padriciano 99, I-34012 Trieste, Italy
d
Department of Food Science, Stocking Hall, Cornell University, Ithaca, New York 14853
e
Centre de Recherche sur la Matière Divisée, University of Orleans & CNRS,
rue de la Férollerie 1B, F-45071 Orléans Cedex 2, France
f
IMPMC-Sorbonne Univ & UPMC-Univ Paris 06, UMR CNRS 7590,
4 Place Jussieu, F-75005 Paris, France
The process of quasi-isothermal dehydration of thin films of pure water and aqueous sugar
monomer and polymer solutions is investigated with a dual experimental and theoretical
approach [1]. A nanoporous paper disk with a homogeneous internal structure was used as a
substrate. This experimental set-up makes it possible to gather thermodynamic data under
well-defined conditions, develop a numerical model and extract needed information about the
dehydration process, in particular the water activity. It is found that the temperature evolution
of the pure water film is not strictly isothermal during the drying process, possibly due to the
influence of water diffusion through the cellulose web of the substrate. The role of sugar and
other more complex systems, including mixed gels, is clearly detectable and its influence on
the dehydration process can be identified, as already presented for non-isothermal conditions
[2-3]. At the end of the drying process, the presence of sugar components, either monomers
or polymers, slow down the diffusion of water molecules through the substrate in a way that
reveals the change of water activity in the low-moisture biosystems. Extension of this type of
characterization to cell monolayers on a polymer support has been investigated, providing a
clear signature of the chemical stresses imposed to the cells. The validity of the experimental
approach and the comparison of the results with other literature findings is discussed.

1

2
3

Heyd, R., Rampino, A., Bellich, B., Elisei, E., Cesàro, A., & Saboungi, M. L. (2014).
Isothermal dehydration of thin films of water and sugar solutions. The Journal of
chemical physics, 140(12), 124701.
Bellich, B., Borgogna, M., Cok, M., & Cesàro, A. (2011). Release properties of
hydrogels: water evaporation from alginate gel beads. Food biophysics, 6(2), 259-266.
Bellich, B., Borgogna, M., Cok, M., & Cesàro, A. (2011). Water evaporation from gel
beads. Journal of thermal analysis and calorimetry, 103(1), 81-88.

11

Imaging water on biological nanostructures
Alexander M. Bittner†,‡




Deparament CIC nanoGUNE, Av. Tolosa 76,
E-20018 Donostia-San Sebastián, Spain

Ikerbasque, Basque Foundation for Science , Alameda Urquijo, 36-5 Plaza Bizkaia
E-48011 Bilbao, Spain

Liquids can interact with nanostructures in multiple ways, for example swelling, formation of
droplets, or adsorption in ultrathin layers of various geometries. For the nanoscale, oils and
ionic liquids are often convenient choices because water has a rather high vapour pressure.
However, water is the biological fluid, which justifies additional efforts, such as
environmental electron microscopy (Fig. 1): This method works at high water vapour
pressures, up to condensation, and offers real time views on the nanoscale. Moreover, it can
be operated in scanning and in scanning transmission modes, the latter with resolutions well
below 10 nm.
As biological objects, filamentous plant viruses [1,2] and electrospun protein fibres [3] were
chosen. Their fibre-like nature allows imaging even below 10 nm size [2-5], and induces new
types of water nanostructures, e.g. wedges. However, detection of the imbibition of 4 nm
wide channels [6] in viruses required standard vacuum electron microscopy: Virus tubes were
filled with aqueous solutions of metal complexes, and repetedly dried, imaged, and rinsed
with water.

Fig. 1: Examples for liquid water in electron microscopy;
droplet on carbon ribbon; pools between plant virus lines.
[1] I. Amenabar, S. Poly, W. Nuansing, E.H. Hubrich, A.A. Govyadinov, F. Huth, R.
Krutohvostovs, L. Zhang, M. Knez, J. Heberle, A. M. Bittner, and R. Hillenbrand, Nature
Communications 4, 2890 (2013).
[2] J. M. Alonso, F. Tatti, A. Chuvilin, K. Mam, T. Ondarcuhu, and A. M. Bittner, Langmuir
29, 14580 (2013).
[3] W. Nuansing, D. Frauchiger, F. Huth, A. Rebollo, R. Hillenbrand, and A. M.
Bittner,Faraday Discussions 166, 209 (2013).
[4] J. M. Alonso, T. Ondarcuhu, and A. M. Bittner, Nanotechnology 24, 105305 (2013).
[5] A. A. Khan, E. K. Fox, M. L. Gorzny, E. Nikulina, D. F. Brougham, C. Wege, and A. M.
Bittner, Langmuir 29, 2094 (2013)
[6] J. M. Alonso, M. L. Gorzny, and A. M. Bittner, Trends in Biotechnology 31, 530 (2013).

12

Supercooled water escaping metastability
F. Aliotta†, P.V Giaquinta‡, R.C. Ponterio†, S. Prestipino‡, F. Saija†, C. Vasi†


Istituto per i Processi Chimico-Fisici, CNR, viale F. Stagno d’Alcontres 37,
I-98158 Messina, Italy

Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina, Contrada Papardo
I-98166 Messina, Italy

The return of supercooled water to stable equilibrium condition is an irreversible process
which takes place adiabatically [1]. In fact, the process is a very fast process and results in the
formation of a liquid-solid mixture at the coexistence temperature.
The solid phase grows up as a dendritic structure. It has been suggested that the formation of
dendrites can promote the release of latent heat at the liquid solid interface [2]. The
investigation of the dendrite formation by fast imaging, while simultaneously monitoring the
local temperature, reveals the existence of two regimes. At supercooling temperature below
266.7 K the process arrives to completions in a very short time (<0.07 s), whereas at higher
temperatures several seconds are needed for the system to reach equilibrium. The boundary
between the two regions is very sharp (< 0.5 K), which suggests an abrupt transition. The
slow process evolves following the same universal path, independently of the initial
supercooling temperature. Even in the presence of a slow process, no heat flux to the
thermostatic bath is revealed. Hence, on a scale involving the whole system, the process
maintains its adiabatic character. The transition between the two processes is explained in
terms of the balance between the local flux of the latent heat released by the growing crystal
and the flux of heat between the equilibrated liquid at the melting temperature and its
environment, still at the initial temperature.

[1] see, e.g., F. Aliotta, P.V. Giaquinta, M. Pochylski, R.C. Ponterio, S. Prestipino, F. Saija,
C. Vasi, J. Chem Phys. 138, 184504 (2013).
[2] M.E. Glicksmann, A.O. Lupulescu, J. Cryst. Growth 264, 541-549 (2004).

13

Protein dynamical transition(s) with and without water
Giorgio Schirò
CNRS – Institut de Biologie Structurale
71 Av. des Martyrs, 38044 Grenoble, Fracne
giorgio.schiro@ibs.fr

Proteins, the molecular machines of living systems, are, at physiological temperatures, highly
anharmonic systems. Anharmonic structural fluctuations are essential to protein biological
function; understanding the origin of their activation is a central topic in biophysics.
Experiments and simulations suggested that the origin is found in the strong dynamical
coupling between proteins and their natural matrix, water.
The use of homopeptides as model systems for proteins allowed us to identify the molecular
contributions to anharmonic dynamics [1] and to obtain a description of the energetics
determining its activation [2]. The use of protein perdeuteration and neutron scattering enabled
us to look at the water matrix dynamics around both globular and intrinsically disordered
proteins and to reveal the nature of water motions triggering the onset of anharmonic protein
dynamics [3]. The recent discovery that water-free protein/polymer hybrids can retain almost
unaffected biological [4] and dynamical [5] properties challenged the idea of an exclusive role
of water in activating biologically relevant protein motions. The analysis of neutron scattering
data on selectively deuterated protein/polymers hybrids provided a physical basis of this waterlike performance in water-free systems [6].
I will present a review of our recent results described above, focusing on quasi-elastic neutron
scattering data from H2O-hydrated deuterated proteins [3] and protein/polymer hybrids [6],
which unveil the structural/dynamical role of external matrix (water in hydrated proteins,
polymer in the hybrids) in triggering the onset of anharmonic protein fluctuations.

[1] G. Schirò, C. Caronna, F. Natali, A. Cupane, J Am Chem Soc 132, 1371 (2010).
[2] G. Schirò, F. Natali, A. Cupane, Phys Rev Lett, 109(12), 128102 (2012).
[3] G. Schirò, F.-X. Gallat, K. Wood, J.-P. Colletier, F. Gabel, J. Wuttke, M. Moulin, M.
Hartlein, A. Orecchini, A. Paciaroni, M. Weik, in preparation.
[4] A. W. Perriman, A. P. S. Brogan, H. Colfen, N. Tsoureas, G. R. Owen, S. Mann, Nat Chem
2, 622 (2010).
[5] F.-X. Gallat, A. P. S. Brogan, Y. Fichou, N. McGrath, M. Moulin, M. Hartlein, J. Combet,
J. Wuttke, S. Mann, G. Zaccai, C.J. Jackson, A. M. Perriman, M. Weik, J Am Chem Soc
134, 13168 (2012).
[6] G. Schir , F.-X. Gallat, A. P. S. Brogan, G. Schneider, S. Mann, A. W. Perriman, M. Weik,
in preparation.

14

Do we really need water models in full, when it comes to studies of
biopolymer conformations?
Artem Badasyan†


Materials Research Laboratory, University of Nova Gorica,
SI-5000 Nova Gorica, SLOVENIA, EU

General concepts of H-bond formation between water and biopolymer repeated units are
discussed assuming that: a) the interaction is short ranged; b) external conditions (P, T) are far
from water critical points and are limited to physiological range.
To provide a toy spin model of dry protein folding, the links between spherically symmetric
contact potentials and spin models are considered. Directional potentials, used to simulate
water are discussed and the link with the Potts spins is explained. The combination of spin
models for water+biopolymer can be simplified by summing out over water degrees of
freedom. Thus we arrive at a model with the spin Hamiltonian, comprised of a single term, but
with renormalised temperature-dependent energy of spin-spin interaction.
We propose and illustrate the use of such a mixed computational/analytical approach on the
example of a hard-sphere polymer model with square-well potential. Comparison with the
recent studies of a much more complex computational models reported from the Debenedetti
group [1, 2] have revealed the qualitatively similar results. Our approach can reproduce the
observed cold and heat denaturation, but at a much smaller computational cost.

Figure 1. Radius of gyration for a hard
sphere pentamer, recalculated using
temperaturedependent transformation.
Depending on the value of the ratio between
the energy of polymer-solvent interaction to
that of polymer-polymer interaction, the
radius of gyration loses monotonic behavior,
thus allowing for reentrant, cold
denaturation.

[1] S. Romero-Vargas Castrillon,́
S. Matysiak, F. H. Stillinger, P. J. Rossky, P. G.
Debenedetti, J. Phys. Chem. B 116, 9963 (2012).
[2] S. Matysiak, P. G. Debenedetti, P.J. Rossky, J. Phys. Chem. B 116, 8095 (2012).

15

Waterscopy in food and biological materials
Dominique Champion, Ali Assifaoui, Olivier Bidault, Adrien Lerbret,
Camille Loupiac, Gaëlle Roudaut.
Team: Physical-Chemistry of Edible Materials.
UMR PAM. AgrosupDijon – Université de Bourgogne.
Bd Petitjean, 21000 Dijon. France.

The quality of food products is governed by its organoleptic properties which are the results
of numerous physical-chemical transformations through its process. When water content is or
is becoming the limiting parameter in food materials, the competitive hydration of the
different components may explain evolutions in the products like crystallization, protein
denaturation, non-enzymatic browning, lipid oxidation… The objectives of food
technologists are to manage these changes in raw food materials in order to obtain either
intermediary ingredients able to be transformed in an industrial way, or stable food products
for consumers, or even new food materials for the market development. To better understand
the effect of hydration in multicomponent mixtures, food sciences use several tools adapted
from material sciences as the glass transition concept for their amorphous or semi-crystalline
states in taking into account the heterogeneity of the material. Water distribution between
ingredients is one of the more difficult parameters to study in composite material and one
way to probe molecule hydration can be to study the mobility at a molecular level.
In this presentation, the main will be to present how complementary techniques like
dynamical mechanical spectroscopy, NMR, EPR and Neutrons Scattering can be used to
determine molecular mobility in composite food material. All examples will be given from
different food domains: biscuit dough, different protein powders … It will underline how the
different techniques can give complementary results at a macroscopic and molecular level but
also at different time scales. Particularly, the molecular interactions with water were
examined to discuss the concept of bound or free water in terms of difference of molecular
mobility.

16

Molecular Density Functional Theory of Water and Application to Solvation
Guillaume Jeanmairet, Maximilien Levesque, Rodolphe Vuilleumier, and Daniel Borgis†


Pôle de Physico-Chimie Théorique, Ecole Normale Supérieure, UMR 8640 CNRS-ENS-UPMC,
24, rue Lhomond, 75005 Paris, France

We present a (classical) molecular density functional theory (MDFT) of water that is
derived from first principles and is based on two classical density fields, a scalar one, the
particle density,
and a vectorial one, the multipolar polarization density. Its
implementation requires as input the partial charge distribution of a water molecule and
three measurable bulk properties, namely the structure factor and the k-dependent
longitudinal and transverse dielectric constants. It has to be complemented by a solutesolvent three-body term that reinforces tetrahedral order at short range. The approach is a
different paradigm from that of standard MD or MC simulations with explicit solvent.
Compared to those methods, it is shown to provide the correct three-dimensional
microscopic solvation profile around molecular solutes, possibly those possessing Hbonding sites, at a computer cost two-three orders of magnitude low er. The computed
solvation free-energies are also discussed, as well as the solvation properties of
hydrophobic solutes of various sizes, from microscopic to mesoscopic.

.

Fig. 1: Three-dimensional water density around a N-methyl-acetamide molecule obtained by
MDFT minimization
[1] G. Jeanmairet, M. Levesque, R. Vuilleumier, and D. Borgis, J. Phys. Chem. Lett. 4, 619
(2013); J. Chem. Phys. 139, 154101 (2013).
[2] V. Sergiievskyi, G. Jeanmairet, M. Levesque, and D. Borgis, J. Phys. Chem. Lett. 5, 1935
(2014).

17

Maximum probability domains for exploring the structure of liquid water
Rodolphe Vuilleumier†,‡ and Federica Agostini§


Ecole Normale Supérieure-PSL Research University, Département de Chimie, 24, rue Lhomond,
75005 Paris, France.

Sorbonne Universités, UPMC Univ Paris 06, PASTEUR, F-75005, Paris, France.
§
Max-Planck Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany

Maximum Probability Domains (MPDs) were first introduced in electronic structure theory
[1] for localizing electron pairs in molecules. Here, we generalize this concept for studying
atomic or molecular densities. These domains are defined by maximizing the probability of
finding one and only one particle in their interior. These regions of space, where atoms or
molecules are well localized, exhibit the local structure of liquids.
After shortly describing how the MPDs can be obtained numerically from molecular
dynamics simulations using the level set method, we will show how they can be used to
explore the local structure of liquid water, up to the second solvation shell. We will compare
liquid water at ambient conditions and at high pressure ( r = 1.23 g/cm3). MPDs can also be
used to study the solvation shell of ions, as will be illustrated in the case of hydrated Na +.
Finally, we will discuss to what extend MPDs can be used to study the dynamics of solvent
shell reorganization.

Fig. 1: Set of one particle Maximum Probability Domains around a water molecule in highpressure liquid water (r = 1.23 g/cm3). The first shell with four water molecules (red and dark
blue) is clearly visible as well as are interstitial molecules (brown, purple and light blue in the
back), competing with the first shell molecules. Part of the second solvation shell is also
resolved (cyan).
[1] E. Cancès, R. Keriven, F. Lodier, and A. Savin, Theor. Chem. Acc. 111, 373 (2004).

18

What gas hydrates tell us about water-gas interactions
Werner F. Kuhs
GZG Abt.Kristallographie, Universität Göttingen, Goldschmidtstr.1, 37077 Göttingen, Germany

The interaction of hydrophobic gases with water can be studied in gas clathrate hydrates in an

exemplary way. It is interesting to note that in gas hydrates the solubility of gases is orders of
magnitude larger than in liquid water. Bridging this “solubility gap” when going from the
liquid to the solid state is a crucial step in the formation of gas hydrates. Notwithstanding
recent efforts by molecular dynamics simulations (albeit with often unrealistic driving forces)
and X-ray reflectometry the transformation of water/ice into gas hydrates is not really
understood, despite its importance e.g. for flow assurance in gas pipelines. Some interesting
insight into the formation process from the liquid can be gained from synchrotron µtomography experiments showing that the growth proceeds from the gas-water interface into
the liquid. Interestingly, these tomography experiments also give very strong evidence for a
markedly different growth pattern when hydrates are formed from so-called “memory water”,
which is obtained from gas hydrate decomposition at low temperature: One possibility to
explain the growth patterns gas is the presence of metastably enriched gas in the liquid phase.
The nature of the interactions of gas molecules with the water frame is born out in the crystal
structure, which can be considered as a systematic hydrophobic hydration producing a
maximum of interaction surface with a minimal amount of water molecules. The gas-water
interactions are most sensitively born out in the lattice constants. The crystalline hydrate
lattice is found to shrink upon inclusion of small polar guest molecules, an effect which is
particularly pronounced upon inclusion of CO2. Interestingly the empty water framework
shows a negative thermal expansion similar to ice Ih which disappears upon the inclusion of
guest molecules; this must mean that the responsible low-frequency H-bond torsion modes
with their negative Grüneisen parameter are reduced by the excluded volume effect of the
guests.
Equally interesting for understanding gas-water interactions are the decomposition
phenomena of gas hydrates. Particularly intriguing are scanning-electron-microscopic (SEM)
observations of gas hydrate surfaces, from which clear evidence for a mesoscopic separation
of gas phase and solid ice is obtained which by all evidence takes place inside the stability
field of gas hydrates. This finding is further supported by synchrotron tomography showing a
thickness of a few μm for this decomposed layer covering the free surface as well as grain
boundaries. Considering the highly dynamic nature of solid ice surfaces we suggest that these
rearrangements are related to mesoscopic hydrophobic interactions in the exposed and
perturbed gas hydrate surface leading to a separation of H-bonded ice (as evidenced by
diffraction) and a gas phase. There is some evidence that this mesoscopic phase separation
process is taking place upon rapid cooling. The resulting sponge-like ice structure with pore
sizes in the order of 100 nm is well-documented by our SEM work and varies somewhat with
the hydrophobic nature of the gas. Similar phenomena were suggested for the liquid state
from computer simulations or observed experimentally and have foundations in theoretical
work on hydrophobic assembly and dewetting phenomena.

19

THz Photon-Echoes in Water?
Janne Savolainen, Saima Ahmed and Peter Hamm
Department Chemistry, University of Zurich, Switzerland
E-mail: p.hamm@pci.uzh.ch
Water is a complex liquid due to the hydrogen-bond network that it forms and that is
responsible for the many peculiarities of water. The associated low-frequency spectrum of
water reports directly on its thermally excited intermolecular degrees of freedom. In this
frequency range, the intermolecular spectrum of water consists of broad, almost featureless
bands at ~600 cm-1 (hindered rotations), ~200 cm-1 (hydrogen bond stretching) and at ~50 cm1
(hydrogen bond bending). The broadening mechanism of these low-frequency intermolecular
degrees of freedom of water and the couplings between them are not understood. In order to
resolve the lineshape functions of these modes, a multidimensional spectroscopy directly in
this frequency range is needed. Here, we demonstrate a hybrid 2D-Raman-THz spectroscopy
of liquid water that circumvents experimental problems of 2D-Raman and 2D-THz
spectroscopy.
The experimental water 2D-Raman-THz time-domain response (Fig. 1a) shows interesting
features beyond the instrument response function. Most interesting is feature V, which extends
along the diagonal (i.e., for t1=t2) further than the instrument response function (Fig. 1b). This
diagonal signal hints towards a THz photon echo, and thus to a heterogeneous distribution of
hydrogen-bond networks, albeit only on a very short 200 fs timescale. This timescale appears
to be too short to be compatible with more extended, persistent structures assumed within a
two-state model of water.

a

b

Fig. 1. (a) 2D-Raman-THz signal of water. (b) Cut along the diagonal for t1=t2 (red
line in panel a), along which the signal (red) extends further than the instrument
response function (blue).

[1] J. Savolainen, S. Ahmed and P. Hamm, “2D-Raman-THz Spectroscopy of Water”
Proc. Natl. Acad. Sci. USA, 110 (2013) 20402

20

The role of water in protein activity (studied by means of Nuclear Magnetic
Resonance and Infrared Spectroscopy)
Francesco Mallamace1,2, Carmelo Corsaro1, Domenico Mallamace3, Sebastiano Vasi1,
Cirino Vasi4 and Sow-Hsin Chen2
1

2

Dept. of Physics, UNIME (Italy);
3

Dept. SASTAS-UNIME (Italy);

Dept. DNSE-MIT (USA);

4

CNR-IPCF, Messina (Italy).

The effect of water on lysozyme is studied in a very large temperature range from 180 to 370
K. By using in a comparative way the Nuclear Magnetic Resonance and the FTIR spectroscopy
(the vibrational modes) we explore this protein system at different hydration level h (h=0.3,
0.37, 0.42). The hydration level h=0.3 is equivalent to a single monolayer of water around the
globular protein. Our interest is focused to study the water role in the protein dynamical
transition (glass transition or the transition from an harmonic solid like behavior to an
anharmonic and liquid like motion) and the irreversible unfolding. We demonstrate also by
considering previous neutron scattering experiments that the protein dynamical transition
belongs to the universal class of dynamical crossover characterizing supercooled liquids and
materials.
By means of a detailed study of the bending vibrational mode of water and of the Amide’s
peptide (Amide I, II and III) we were able to follow the dynamics of the complex hydrogen
bond (HB) network formed between water and hydrophilic moieties of the protein. In particular
the Amide II Infrared region (1450 – 1580 cm-1) contains structural information about the
protein conformation reflected in the bending mode of NH groups and in the stretching mode
of CN groups. Both these groups are involved in the formation of hydrogen bonds, the NH in
a direct way whereas the CN indirectly throughout the carbonyl oxygen, determining the water
accessible regions. More precisely these bonds have different character, whereas one is proton
donor the other is proton acceptor by linking hydrophilic groups of the same and/or different
peptides. The thermal evolution of the spectral features regarding these two contributions
allows identifying that the dynamical crossover observed for water coincides with that of the
protein dynamical transition. We stress that we are able to demonstrate at a molecular level the
interaction of water with the protein peptides and how via the HB it drives the protein activity.
Furthermore, the combination of FTIR, Neutron Scattering and NMR data (under a novel
interpretation) allows us to clarify some of the underlying mechanisms that govern the
reversibility of the folding-unfolding and irreversible denaturation processes of the protein. In
particular, new NMR observations at the temperature above and below the protein irreversible
unfolding (TD) show that folding-unfolding process takes place as a function of the
temperature; we observe that T acts as a control parameter of the measured nuclear
magnetization M(T). Whereas far from this singular temperature the M(T) behavior is
Arrhenius around it, for a large T-interval the system explores the funneled energy landscape
showing a power law behavior. On these bases, by taking advantage of the polymer physics we
propose this complex process (protein folding/unfolding) as a sort of sol-gel transition driven
by water as the cross-linker between different protein peptides, an with TD as the percolation
threshold temperature.

21

Differential scanning calorimetry and pressure-dependent elastic
neutron scattering provide new experimental evidence for a LiquidLiquid Phase Transition in deeply cooled confined water
A. Cupane,1 M. Fomina1, J. Peters2,3, I. Piazza1, and G. Schirò4
1

University of Palermo, Dept. of Physics and Chemistry,
via Archirafi 36, 90123 Palermo, Italy.
2
Institut Laue Langevin, F-38042 Grenoble Cedex 9, France
3
Université Joseph Fourier, F-38041 Grenoble Cedex 9, France
4
CNRS - Institut de Biologie Structurale, 6 rue Jules Horowitz, 38000 Grenoble, France
Email: antonio.cupane@unipa.it
In this work we investigate, by means of Elastic Neutron Scattering (ENS), the pressure
dependence of Mean Square Displacements (MSD) of hydrogen atoms of deeply cooled water
confined in the pores of a 3-dimensional disordered SiO2 xerogel. The “pressure anomaly”
typical of supercooled water (i.e. a MSD increase with increasing pressure) is observed in our
sample at all the temperatures investigated; however, contrary to previous simulation results,
the pressure effect is much smaller at 210 K than at 250 K. ENS data are complemented by
differential scanning calorimetry data that put in evidence, besides the second order-like glass
transition at about 170 K, a first order-like transition occurring at about 235 K that, in view of
the neutron scattering results, can be attributed to a liquid-liquid phase transition. Taken
together our results give convincing experimental evidence of the existence of a Liquid-Liquid
Phase Transition in deeply cooled confined water, from a Low Density Liquid (LDL) phase
predominant at 210K to a High Density Liquid (LDL) phase predominant at 250K.

.

Fig. 1: Panel a): calorimetric upscan of silica xerogel at h=0.42 (left scale, black line) and its
derivative (right scale, red line). Grey dotted lines indicate the temperatures of the second
order-like glass transition and of the first order-like liquid-liquid transition. Panel b):. R(P) =
MSD(P)/MSD(P = 20bar) as a function of pressure; black open circles: T = 210 K; red circles:
T = 250 K. Dashed lines are linear fits.

22

How hydration water affects the stability of proteins
Valentino Bianco and Giancarlo Franzese
Departament de Física Fonamental, Universitat de Barcelona,
Martí Franquès 1, 08028 Barcelona, Spain
The mechanisms of cold- and pressure-denaturation of proteins are matter of debate, but it is
commonly accepted that water plays a fundamental role in the process. Here we show that by
taking into account only the free-energy changes associated to the hydration water it is
possible to rationalize the stability of a protein against heating, cooling, pressurization and
depressurization. To this goal we adopt a coarse-grain model for hydration water [1–4]. We
reproduce the typical elliptic shape of the protein stability region in the pressure-temperature
plane and show that the temperature and pressure-denaturation could arise solely from waterwater hydrogen bonds that at a hydrophobic interface are stronger and more compressible
than in bulk.
References
[1] G. Franzese, V. Bianco, and S. Iskrov, Water at interface with proteins, Food Biophysics
6, 186 (2011).
[2] V. Bianco, S. Iskrov, and G. Franzese, Effect of hydrogen bonds on protein stability, J.
Biol. Phys. 38, 27 (2012).
[3] G. Franzese, and V. Bianco, Water at Biological and Inorganic Interfaces, Food
Biophysics, 8, 153 (2013).
[4] V. Bianco and G. Franzese, Critical behavior of a water monolayer under hydrophobic
confinement, Scientific Reports (Nature Publishing Group) 4, 4440 (2014).

23

The Widom Line of Water
Paola Gallo,†


Dipartimento di Fisica, Università Roma Tre, Via della Vasca Navale 84,
I-00146 Roma, Italy

In this talk I shall summarize recent results from computer simulations addressed to
important issues related to the Widom line of water both in the supercritical and in the
supercooled states. The Widom line is the line of convergence of the maxima of the
thermodynamic response functions upon approaching the critical point. The characterization
of this line is very important both in the supercooled and in the supercritical state and it can
be found upon approaching respectively the liquid-liquid and the liquid gas critical points.
We study the thermodynamic properties of water in the supercritical region by comparing
experimental results and computer simulation results along the isobars. We find that the lines
connecting the maxima of the thermodynamic response functions converge upon approaching
the critical point in a single Widom line separating a liquid-like region from a gas-like region.
We also show that the Widom line in supercritical water is connected to the crossover from a
liquid like to a gas-like behaviour of the transport coefficients [1].
In the supercooled states the characterization of the Widom line in the bulk phase by
computer simulations has been well established. We characterized the Widom line in
hydrophilic [2,3], amphiphilic [4] and hydrophobic [5] aqueous solutions. Depending on the
solute, the experimental determination of the LLCP can be eased as computer simulations
show that its position is shifted in the thermodynamic planes with respect to the bulk. I will
show that the Widom line emanating from the LLCP can be connected to dynamics in
solutions. Dynamics crossovers are associated to the crossing of the Widom line both for the
Jagla liquid with hard spheres [5] and for the aqueous solutions of NaCl [6,7] and the results
found in solutions are comparable to those found in the bulk [8].
[1] D. Corradini, M. Rovere and P. Gallo, in preparation (2014).
[2] D. Corradini, M. Rovere and P. Gallo, J. Chem. Phys. 132, 134508 (2010).
[3] D. Corradini and P. Gallo, J. Phys. Chem. B. 115, 14161 (2011).
[4] D. Corradini, Z. Su, H.E. Stanley and P. Gallo, J. Chem. Phys. 187, 184503 (2012).
[5] D. Corradini, P. Gallo, S.V. Buldyrev and H.E. Stanley, Phys. Rev. E 85, 051503 (2012).
[6] P. Gallo, D. Corradini and M. Rovere, Mol. Phys, 109, 2069 (2011).
[7] P. Gallo, D. Corradini and M. Rovere, J. Chem. Phys. 139, 204503 (2013).
[8] P. Gallo and M. Rovere, J. Chem. Phys., 137, 164503 (2012).

24

Water as a Multiscale Multidynamical System
Michele Parrinello
Department of Chemistry and Applied Biosciences, ETH, 8092 Zurich, Switzerland
and
Facoltà di Informatica, Istituto di Scienze Computazionali, Università della Svizzera italiana, via
Giuseppe Buffi 13, 6900 Lugano, Switzerland

It has long been known that water is a network forming liquid characterized by the presence
of hydrogen bonded rings, whose structure is continuously formed and broken. We
performed a number of Car-Parrinello ab-initio simulations to study how this is reflected ion
the medium range structure of water and on the behavior of important solutes like water ions
or ionic salts. A useful tool will be description of water as a collection of directed rings. We
find that mobility of proton in water is characterized by considerable dynamical heterogeneity
where period of strong activity are followed by periods of rest and in which several length
scales are involved. We also explain the contrasting effect of CsI and NaCl on the diffusion
coefficient of water [1] with subtle changes in the water structure fluctuations rather than in
their structure making structure breaking ability. Also here dynamical heterogeneity is crucial
to explain this effect which is not captured by commonly used empirical potentials.
[1] Kim JS, Wu Z, Morrow AR, Yethiraj A, Yethiraj A (2012) J Phys Chem B
116(39):12007–12013

25

Supercooled water: liquid-liquid coexistence and complex crystallization in
the ST2 model
Fausto Martelli,† Jeremy C. Palmer,‡ Pablo G. Debenedetti‡ and Roberto Car†



Department of Chemistry, Princeton University, 08544 Princeton, NJ, USA
Departament of Chemical and Biological Engineering, Princeton University,
08544 Princeton, NJ, USA

We have computed the free energy landscape of ST2 water in the supercooled regime (228.6
K and 2.4 kbar) using several state-of-the-art computational techniques, including umbrella
sampling and metadynamics. Such results conclusively demonstrate coexistence between two
liquid phases, a high-density liquid (HDL) and a low-density liquid (HDL), which are
metastable with respect to cubic ice. We show that the three phases have distinct structural
features characterized by the local structure index (Ī) and ring statistics. We also show that ice
nucleation, should it occur, does so from the low-density liquid. Interestingly, we find that the
number of 6-member rings increases monotonically along the path from HDL to LDL, while
non-monotonic behavior is observed near the saddle point along the LDL-ice Ic path. This
behavior indicates a complex re-arrangement of the H-bond network, followed by progressive
crystallization.
DOE: DE-SC0008626 (F. M. and R.C.)

.

Fig. 1: Free energy projection on the Ī-Q6 plane. We can recognize three basin: the HDL at
low values, the LDL at low Q6 and intermediate I, and cubic ice at high values. The inset
shows the mean value of the ring size distribution as a function of Q6.
[1] J. C. Palmer, F. Martelli, Y. Liu, R. Car, A. Panagiotopoulos, P. G. Debenedetti, Nature,
Accepted (2014)

26

Water at the Interface with a Charged Surface
Fabio Bruni
Dipartimento di Scienze, Università degli Studi di Roma Tre,
Via della vasca navale, 84,
00146 Rome, Italy

Laponite is a synthetic disc-shaped crystalline clay belonging to the family of swelling
smectites. To date it is the most widely studied synthetic clay on account of its special
chemical and physical properties, making it promising both as ''smart'' material suitable for
several industrial and biomedical applications and as model system for fundamental studies
on phase transitions and water molecules-charged surfaces interaction [1].
We have performed dielectric relaxation experiments on laponite powder with about 4 water
layers of hydration around each laponite disc (Fig. 1A), over a broad interval of frequencies,
ranging from 10-3 to 107 Hz, and over the temperature range between 150 and 300 K. The aim
of this work is to study the orientational dynamics of water molecules close to the laponite
surface. In particular, we examined the temperature dependence of the relaxation process
assigned to the collective dynamics of the hydrogen bond (HB) network.
Preliminary results indicate the presence of two dynamical crossovers of this collective
relaxation time (Fig. 1B): the first one (at about 260 K) identifies two different VogelFulcher-Tamman (VFT) regimes, while at about 170 K a second crossover identifies a
dynamical transition from a VFT to a Arrhenius temperature dependence of the relaxation
time.
This situation is quite similar to what previously observed for water molecules in the first
hydration shell of a globular protein [2]. In this latter case, a coarse-grained model of water
molecules helped us to attribute the observed crossovers to the thermodynamics of the HB
network, with two specific heat maxima. The high temperature maximum is caused by
fluctuations in the HB formation, while the low temperature maximum is due to the
cooperative reordering of the HB network.
10

relaxation time [s]

10
10
10
10
10
10

4

2

0

-2

-4

laponite + 4 water layers

-6

-8

3.5

4.0

4.5

5.0

5.5 6.0x10-3

-1

1/T [K ]

Fig. 1: (A, left panel) A snapshot of the sample showing the laponite crystal in the middle
and the first layers of water molecules on the left and right side. (B, right panel) The
collective relaxation time of the hydrogen bond network, showing two crossovers.
[1] Ruzicka B. et al., Soft Matter 7, 1268-1286 (2011).
[2] Mazza et al., PNAS, 108, 19873 (2011).

27

Water-induced surface passivation of amino acids
Jordi Fraxedas,† A. Verdaguer†, E. Barrena§ and C. Ocal§


ICN2 - Institut Català de Nanociència i Nanotecnologia, Campus UAB, 08193, Bellaterra
(Barcelona), Spain and CSIC - Consejo Superior de Investigaciones Científicas, ICN2 Building,
08193 Bellaterra (Barcelona), Spain
§

Institut de Ciència de Materials de Barcelona ICMAB-CSIC, Campus de la UAB,
E-08193 Bellaterra, Spain

L-alanine is an example of an amphiphilic crystal, exhibiting two surfaces, (011) and (120),
with contrasting behavior when exposed to water: (011) is hydrophilic while (120) is
hydrophobic [1]. We have studied the interaction of water with freshly cleaved (011) surfaces
of L-alanine single crystals as a function of relative humidity (RH) combining different
scanning force microscopy (SFM) techniques, both in contact and noncontact operational
modes (lateral force, molecular resolution contact mode, and electrostatic modes). We have
shown that water molecules strongly interact with the initial hydrophilic (011) surface even at
low RH values (< 10%), promoting diffusion of L-alanine molecules and creating a two level
landscape formed by terraces and islands that undergo 2D Ostwald ripening. Both surface
levels exhibit the same nature and crystallographic structure but with a 180 degrees rotated
orientation as revealed by the friction asymmetry observed in lateral force microscopy
measurements. A structural model based on energetic and geometric arguments is presented in
which molecules lie flat in a low density ordered arrangement uniaxially matching the
underlying (011) crystal orientation. This watermediated surface reorganization can be seen as
a surface self-passivation process, with an associated hydrophilic-hydrophobic transition
induced by water, with promising implications in the investigation field of biomolecules [2].
.

Fig. 1: Side views of the (a) initial (011) surface and of (b) resulting structure induced by water.
[1]
J. J. Segura, A. Verdaguer, M. Cobián, E. R. Hernández, J. Fraxedas, J Am Chem Soc
131, 17853 (2009).
[2]
J. J. Segura, A. Verdaguer, L. Garzo´ n, E. Barrena, C. Ocal, J. Fraxedas, J Chem Phys
134, 124705 (2011).

28

Electron density functional optimization for water
Michelle Fritz,† Marivi Fernandez-Serra,‡ Mike J. Gillan,§ and Jose M. Soler†


Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid,
E-28049 Madrid, Spain


Department of Physics and Astronomy, Stony Brook University,
Stony Brook, NY 11794-3800, USA

§

University College London, London Center for Nanotechnology,
London WC1H 0AH, England

Despite much effort during the last 20 years, the simulation of liquid water by ab initio
electron density functional theory (DFT) is still rather unsatisfactory, compared with that of
empirical force fields. The coexistence of essential interactions, with very different strengths,
makes this system extremely sensitive to minor changes in the functionals, and we lack a
systematic knowledge on what functional changes would improve its description.
Here we describe a method, data projection onto parameter space (DPPS), to optimize an
energy functional of the electron density, so that it reproduces a dataset of experimental
magnitudes. In its unconstrained version, it gives the optimal functional form to fit the data,
providing clues in the search for new ab initio functionals.
Additionally, we present a scheme, based on Bayes theorem, to constrain the optimized
functional not to depart unphysically from existing ab initio functionals. The resulting
functional maximizes the probability of being the “correct” parametrization, in the sense of
Bayes theory, for a given functional form, like the generalized gradient approximation
(GGA).

29

Water dissociation and proton-hopping: DFT and beyond
A. Marco Saitta,† F. Saija,‡ G. Cassone,† P.V. Giaquinta,‡ M. Dagrada,† M. Casula,† S.
Sorella,§ and F. Mauri†


Institut de Minéralogie et de Physique des Milieux Condensés, Université Pierre et Marie Curie –
Sorbonne Universités, 75005 Paris, France

IPCF – CNR and Università di Messina, 98158 Messina, Italy
§
Scuola Internazionale Superiore di Studi Avanzati (SISSA/ISAS), 34014 Trieste, Italy

Proton hopping is a crucial phenomenon in science and engineering, since it is at the origin of
many important properties from ionic conduction to acid/base behavior, to life sciences. In
this talk the occurrence of this phenomenon under extreme conditions of electric field will be
presented and discussed. At first, we will present a study of liquid water under field, whose
detailed description at a microscopic level is difficult to achieve experimentally. Here we
report its first ab initio molecular-dynamics study [1]. We observe that the hydrogen-bond
length and the molecular orientation are significantly modified at low-to-moderate field
intensities. Fields beyond a threshold of about 0.35 V/Å are able to dissociate molecules and
sustain an ionic current via a series of correlated proton jumps. Upon applying even more
intense fields (~1.0 V/Å), a 15%-20% fraction of molecules are instantaneously dissociated
and the resulting ionic flow yields a conductance of about 7.8 Ω-1 cm-1, in good agreement
with experimental values. Our study has been extended to ordinary ice Ih and its ferroelectric
counterpart ice XI, showing a counterintuitive interplay between order, dissociation and
protonic current [2], while preliminary results on salty solutions under external fields indicate
that the presence of ions significantly enhances molecular dissociation with respect to pure
liquid water, with potentially important consequences in electrolytic cells and
electrochemistry [3].
However, although proton hopping is rather fairly and qualitatively described within standard
density functional theory, achieving a more accurate and quantitative description requires
both a more advanced inclusion of electronic correlations, and a proper treatment of the
quantum nature of the proton. We present here the results of our fully Quantum Monte Carlo
study of the Zundel ion H5O2+, with a quantitative description of its energy landscape that
matches the most advanced, and computationally demanding, quantum chemistry methods
[4].

Fig. 1: Left: Snapshot of the combined dissociation/diffusion event in water.
Right: energy landscape of the Zundel ion in QMC and DFT.
[1] A. M. Saitta, F. Saija, P. V. Giaquinta, Phys. Rev. Lett. 108, 207801 (2012).
[2] G. Cassone, P. V. Giaquinta, F. Saija, A. M. Saitta, J. Phys. Chem. B, submitted (2014).
[3] G. Cassone, P. V. Giaquinta, F. Saija, A. M. Saitta, in preparation (2014).
[4] M. Dagrada, M. Casula, A. M. Saitta, S. Sorella, F. Mauri, J. Chem. Theo. Comp.,
submitted (2014).

30

Phase Diagram of Salty Ice under Pressure
Adriaan-Alexander Ludl*, Livia E. Bove*, Stefan Klotz*, A. Marco Saitta*, Mathieu Salanne+
* Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie,
UMR CNRS 7590
+ Laboratoire Physicochimie des Electrolytes et Nanosystèmes Interfaciaux,
UMR CNRS 8234
LabEx MATISSE
Université Pierre et Marie Curie
Paris, France
Before the recent discovery of the existence of high-pressure ice phases highly loaded in salt
[1], the belief was that water freezing, either by cooling or by applying pressure, would result
in salt expulsion from the ice lattice with consequent formation of pure ice crystals and salthydrates. We have shown that it is possible to incorporate ions in the ice lattice by recrystallising amorphous phases under high pressure.
Although NaCl-water solutions are not as good glass formers as concentrated LiCl-water
solutions [1], they can be amorphised at ambient pressure by fast quenching at liquid nitrogen
temperature [2]. The solutions close to the eutectic concentration (R=10) vitrify in a
structurally compact form similar to the relaxed high-density amorphous phase of pure water
(e-HDA). In contrast with LiCl solutions [3], the HDA-HDL boundary is not accessible due
to the nucleation of cubic ice upon annealing at ambient pressure. However, when the
amorphous solid is annealed under high pressure (4 GPa) it crystallizes, like concentrated
LiCl solutions [4], in a structural form similar to ice VII.
[1] Klotz, S., Bove, L. E., Strässle, T., Hansen, T. C., Saitta, A. M. The preparation and structure of
salty ice VII under pressure. Nature Materials 8, 405-409 (2009).
[2] Angell, C. A., Sare, E.J. Glass-Forming Composition Regions and Glass Transition Temperatures
for Aqueous Electrolyte Solutions. The Journal of Chemical Physics 52, 1058 (1970).
[3] Ludl, A.-A., Bove, L. E., Klotz, S. in preparation.
[4] Bove, L. E., Klotz, S., Philippe, J., Saitta, A. M. Pressure-Induced Polyamorphism in Salty Water.
Physical Review Letters 106, (2011).

31

Microscopic rationalization of the excess enthalpy of the water + methanol
system using molecular simulation
Diego González-Salgado,1 Claudio A. Cerdeiriña,1 and Enrique Lomba2
1

Universidad de Vigo, Departamento de Física Aplicada, As Lagoas s/n, 32004, Ourense, Spain.
2

Instituto de Química-Física Rocasolano, CSIC, Serrano 119, E-28006 Madrid, Spain.

Aqueous solutions of methanol have been the subject of numerous studies because of both
potential practical applications and relevance on basic grounds. Two main scientific
communities have paid attention to them: biochemists and biologists, who have envisioned
that a complete understanding of this system can help to rationalize that of more complex
aqueous solutions containing biological macromolecules, and chemical physicists, who have
sought for a correct explanation of its intriguing thermodynamic behavior. The 1945 picture
by Frank and Evans [1], which has been traditionally regarded a reliable microscopic basis
for the {water + methanol} mixture and other aqueous solutions, is still an actual matter of
debate: for instance, neutron scattering experiments have provided an alternative view [2].
Using Monte Carlo molecular simulation, we provide a microscopic rationalization of the
excess enthalpy of the {water + methanol} system. The intermolecular potential employed
was constructed from the TIP4P/2005 [3] and the OPLS [4] models of water and methanol.
The Lennard-Jones cross parameters were set in order to give a good quantitative description
of excess volumes and excess enthalpies. On adopting a two-liquids approach, the excess
enthalpy is split into two pieces corresponding to water and methanol molecules, respectively.
Those contributions are in turn divided into a hydrogen-bond part and another one arising
from the remaining interactions. Hydrog
en bonding is found to be important, but its contribution to the (total) excess enthalpy is
virtually hidden.
References
[1] H. S. Frank and M. W. Evans, J. Chem. Phys. 13, 507 (1945)
[2] S. Dixit, J. Crain, W. C. K. Poon, J. L. Finney, and A. K. Soper, Nature 416, 829 (2002).
[3] J. L. F. Abascal and C. Vega, J. Chem. Phys. 123, 234505, (2005).
[4] W. L. Jorgensen, J. Phys. Chem. 90, 1276 (1986).

32

Computer simulation study of surface wave dynamics
at the crystal–melt interface
Jorge Benet, Luis G. MacDowell and Eduardo Sanz
Departamento de Química Física, Facultad de Ciencias Químicas,
Universidad Complutense de Madrid, 28040 Madrid, Spain

We study, by means of computer simulations, the crystal-melt interface of three different
systems: hard-spheres, Lennard Jones and the TIP4P/2005 water model. In particular, we
focus on the dynamics of surface waves. We observe that the processes involved in the
relaxation of surface waves are characterized by distinct time scales: a slow one related to the
continuous recrystallization and melting, that is governed by capillary forces; and a fast one
which we suggest to be due to a combination of processes that quickly cause small
perturbations to the shape of the interface (like e.g. Rayleigh waves, subdiffusion, or
attachment/detachment of particles to/from the crystal). The relaxation of surface waves
becomes dominated by the slow process as the wavelength increases. Moreover, we see that
the slow relaxation is not influenced by the details of the microscopic dynamics. In a time
scale characteristic for the diffusion of the liquid phase, the relaxation dynamics of the
crystal-melt interface of water is around one order of magnitude slower than that of Lennard
Jones or hard spheres, which we ascribe to the presence of orientational degrees of freedom
in the water molecule. Finally, we estimate the rate of crystal growth from our analysis of the
capillary wave dynamics and compare it with previous simulation studies and with
experiments for the case of water.

33

Molecular modelling of high-pressure hydrogen clathrates
Grigory S. Smirnov,†‡ Vladimir V. Stegailov†‡


Joint Institute for High Temperatures of the Russian Academy of Sciences,
Izhorskaya st. 13 Bd.2, Moscow 125412, Russia;


Moscow Institute of Physics and Technology (State University),
Institutskij per. 9, Dolgoprudny 141700, Russia

Gas hydrates are crystalline water-based inclusion compounds in which guest
molecules are trapped inside cavities of the hydrogen-bonded water network. Several
clathrates and filled-ice structures are known. Structure type primarily depends on guest size,
temperature and pressure. Phase diagram of H2+H2O system has attracted great interest due to
possibility of hydrogen storage and transportation. The pure hydrogen hydrates form at very
high pressure, however, the addition of a promoter molecule, for example, tetrahydrofuran or
methane, significantly reduce the formation pressure. Practical usage of hydrogen hydrates
requires knowledge of phase diagram in a wide range of pressures and temperatures.
A new clathrate phase of water−hydrogen systems was reported by Efimchenko et al.
[1] at about 253 K and 5 kbar and by Strobel et al.[2] at about 170 K and 7 kbar. X-ray
diffraction patterns do not allow determination of its structure unambiguously. In this work,
we perform classical molecular dynamics simulation of hydrogen hydrates and select two
possible structures. One of these structures is not a typical clathrate and has never been
observed for hydrates [3].

[1] V.S. Efimchenko et al., J Alloys Compd 509, S860 (2011).
[2] T.A. Strobel, M. Somayazulu, R.J. Hemley, J Phys. Chem. C, 115, 4898 (2011).
[3] G.S. Smirnov, V.V. Stegailov, J. Phys. Chem. Lett. 4, 3560 (2013).

34

Unraveling the complex nature of the hydrated electron
Pavel Jungwirth
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech
Republic, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
E-mail: pavel.jungwirth@uochb.cas.cz

Interaction of water with ionizing radiation is, in addition to direct DNA damage,
causing radiation damage in living organisms and it is also important for nuclear waste
treatment. Upon photoionization in water an electron and a cationic hole are formed, and we
have followed the fate of both. In the talk, I focus on the structure of the hydrated electron
which, despite its key role in radiative processes in water, has remained elusive. The traditional
cavity model has been questioned recently, but the newly suggested picture of an electron
delocalized over a region of enhanced water density is controversial. Here, we present results
from ab initio molecular dynamics simulations, where not only the excess electron but also the
valence electrons of the surrounding water molecules are described quantum mechanically.
Unlike in previous one-electron pseudopotential calculations, many-electron interactions are
explicitly accounted for. The present approach allows for partitioning of the electron solvated
in liquid water into contributions from an inner cavity, neighboring water molecules, and a
diffuse tail. We demonstrate that all three of these contributions are sizable and, consequently,
important, which underlines the complex nature of the hydrated electron and warns against
oversimplified interpretations based on pseudopotential models. We also investigate the
electron solvated at the water surface. The present results clearly demonstrate that the surface
electron is mostly buried in the interfacial water layer, with only about ten percent of its density
protruding into the vapor phase. Consequently, it has structure which is very similar to that of
an electron solvated in the aqueous bulk.

35

Computer simulations of heat transport in water
Fernando Bresme
Computational Chemical Physics, Department of Chemistry,
Imperial College London, SW7 2AZ, UK
The investigation of water has attracted the interest of experimentalists and theoreticians.
There are now well-established empirical water models that describe surprisingly well the
thermodynamic and coexistence properties of water and ice in a wide range of thermodynamic
conditions. Similarly, steady progress is being made in the ab initio simulation of water.
Despite all these advances the investigation of heat transport in water has been largely
neglected. This is surprising since water features the largest thermal conductivity of any
molecular liquid. Also, the thermal conductivity of water features an anomalous dependence
with temperature. The high thermal conductivity of water contributes towards the efficient
thermal regulation of living organisms, e.g., by providing a medium to efficiently relax excess
energy in biomolecules. Water is also widely used in heat management applications at
industrial and nanomaterial levels. Hence, a microscopic knowledge of the mechanisms
determining heat transport in bulk and at interfaces is desirable. In this talk, I will discuss our
recent work on non-equilibrium molecular dynamics simulations of heat conduction in bulk
water and in water-nanomaterial/biomolecule interfaces. Simulations provide a unique
approach to quantify heat transport in a wide range of conditions, including extreme pressures,
nanoscale interfaces and supercooled states, which are difficult to tackle using current
experimental approaches.
References:
 F. Bresme, J.W. Biddle, J.V. Sengers and M.A. Anisimov, “Minimum in the thermal
conductivity of supercooled water: a computer simulation study”, J. Chem. Phys., 140,
(2014).
 J. Armstrong, A. Lervik and F. Bresme, “Enhancement of the thermal polarization of
water via heat flux and dipole moment dynamic correlations”, J. Phys. Chem. B, 117,
14817-14826 (2013).
 F. Bresme and F. Romer, “Heat transport in liquid water at extreme pressures: a nonequilibrium molecular dynamics study”, J. Mol. Liq., 185, 1-7 (2013).
 F. Romer, Z. Wang, S. Wiegand and F. Bresme, “Alkali Halides under Thermal
Gradients: Soret coefficients and heat transfer mechanisms”, J. Phys. Chem.B, 117,
8209-8222 (2013).
 F. Romer, A. Lervik and F. Bresme, “Nonequilibrum molecular dynamics simulatios of
the thermal conductivity of water: a systematic investigation of the SPC/E and TIP4/2005
models”, J. Chem. Phys. 137, 074503 (2012).
 F. Bresme, A. Lervik, D. Bedeaux and S. Kjelstrup, “Water polarization under thermal
gradients”, Phys. Rev. Lett., 101, 020602 (2008).

36

Recent experiments on metastable water
F. Caupin, C.P. Tripathi, G. Pallares, M. El-Mekki Azouzi,
A. Dehaoui, L.P. Singh, B. Issenmann


Institut Lumière Matière, Unité Mixte de Recherche 5306
Université Lyon 1, Centre National de la Recherche Scientifique, Université de Lyon
and Institut Universitaire de France, 69622 Villeurbanne Cedex, France

The key to water anomalies lies in its metastable liquid phase. Indeed, the various available
theoretical scenarios predict distinct behaviors [1]. In supercooled water, several
thermodynamic quantities could either diverge or go through an extremum. Dynamic
heterogeneities might occur, which could be at the origin of the decoupling between viscosity
and translational diffusion. In liquid water metastable with respect to its vapor, i.e. at negative
pressure, predictions for the shape of the line of density maxima also differ.
We will review the recent experiments in our group aimed at extending the knowledge of the
equation of state of water at negative pressure [2, 3], and of the viscosity of supercooled
water [4].
[1] K. Stokely, M.G. Mazza, H.E. Stanley, G. Franzese. Effect of hydrogen bond
cooperativity on the behavior of water. Proc Natl Acad Sci USA 2010, 107, 1301–1306.
[2] K. Davitt, E. Rolley, F. Caupin, A. Arvengas, S. Balibar. Equation of state of water under
negative pressure. J. Chem. Phys. 2010, 133, 174507.
[3] M. El Mekki Azouzi, C. Ramboz, J.-F. Lenain, F. Caupin. A coherent picture of water at
extreme negative pressure. Nat Phys. 2013, 9, 38–41.
[4] J. Hallett. The temperature dependence of the viscosity of supercooled water. Proc. Phys.
Soc. 1963, 82, 1046-1050.

37

Freezing of water from computer simulations : Thermodynamic and Kinetic aspects.
C. Vega, E.Sanz , C. Valeriani, J.L.F.Abascal, J.R.Espinosa, E.G.Noyaa) , J.L.Aragones, M.M.Conde
and M.A.G.Gonzalez
Departamento de Quimica Fisica
Facultad de Ciencias Quimicas
Universidad Complutense
28040 Madrid
a)Instituto de Quimica Fisica Rocasolano
Consejo Superior de Investigaciones Cientificas (CSIC)
C/ Serrano 119
28006 Madrid

Among all the freezing transitions, that of water into ice is probably the most relevant to biology,
physics, geology or atmospheric science. Computer simulations can be used to locate the coexistence
conditions for a certain water model. Two procedures can be used to locate the coexistence. In the first
one free energy calculations must be performed for the fluid and solid phases to locate the coexistence
point. Although the free energy of the fluid phase can be determined easily, for the solid phase one must
use special methods as for instance the Einstein crystal method. In this work we shall illustrate how to
perform free energy calculations for the solid phases of water (ices) using a Molecular Dynamics package
as GROMACS.[1] The second route to phase equilibrium is the direct coexistence method, where the
two coexistence phases are located within the same simulation box. We shall present results illustrating
that the direct coexistence method is efficient , not only for ice Ih, but for the rest of high pressure polymorphs of water. Besides we shall discuss two issues related to the use of direct coexistence simulations:
its stochastic character [2] and in the particular case of water the subtle issue of the proton ordering of
ices ( with no disorder, partial disorder or complete disorder) [3]. The direct coexistence method can also
be used to analyze the melting point of finite size clusters of ice embedded within a supercooled sample
of liquid water. In this way the size of the critical cluster for the homogeneous freezing of water can be
evaluated. For temperatures between -15 and -35 degrees below freezing the size of the critical clusters
varies from 8000 molecules to 600. The interfacial ice-water free energy can be estimated by using the
expression of Classical Nucleation Theory for the size of the critical cluster (we obtained a value of around
29mN/m in good agreement with experimental reported values). After determining the interfacial free
energy, the free energy barrier for nucleation of ice can be estimated. The free energy barrier varies from
500kT at -15 Celsius to about 300kT at -20 Celsius. These high barriers strongly suggest that homogeneous ice nucleation is extremely unlikely above -20 Celsius and that freezing above this temperature
must be necessarily heterogeneous.[4] The nucleation rate of ice for TIP4P/2005 at the locus of maximum
compressibility of supercooled water at room pressure (located on the Widom line) is negligible so that
, the maximum in compressibility in this model can not be attributed to the transient formation of ice [5].
[1] J. L. Aragones, E. G. Noya, C. Valeriani and C. Vega J.Chem.Phys. 139 034104 (2013)
[2] J. R. Espinosa and E. Sanz and C. Valeriani and C. Vega J.Chem.Phys. 139 144502 (2013)
[3] M. M. Conde and M. A. Gonzalez and J. L. F. Abascal and C. Vega J.Chem.Phys. 139 154505 (2013)
[4] E. Sanz and C. Vega and J. R. Espinosa and R. Caballero-Bernal and J.L.F. Abascal and C.Valeriani
J. Am. Chem. Soc. 135 15008 (2013)
[5] D. T. Limmer and D. Chandler, J. Chem. Phys. 138, 214504 (2013)

38

Crystallization of Water Nanoparticles
Valeria Molinero
Department of Chemistry, The University of Utah,

Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers
in the troposphere and tropopause. These aerosols contain water, salts and organics,
depending on their source. The internal structure and phase state of these aqueous aerosols is
key for their reactivity and physical properties. Nevertheless, it cannot yet be determined in
experiments. In this presentation I will discuss our recent work on modelling equilibrium and
non-equilibrium crystallization of ice, Ostwald ripening, vitrification and internal structure in
nanoparticles of water and water-salt solutions using molecular simulations.
1. Johnston, J.C. & Molinero, V. Crystallization, Melting, and Structure of Water Nanoparticles at
Atmospherically Relevant Temperatures. Journal of the American Chemical Society 134, 6650-6659
(2012).
2. Hudait, A. & Molinero, V. Ice Crystallization in Ultrafine Water-Salt Aerosols: Nucleation, Ice-Solution
Equilibrium and Internal Structure. Journal of the American Chemical Society DOI: 10.1021/ja503311r
(2014).

39

A new metastable form of ice and its role
in the homogeneous nucleation of water
John Russo,† Flavio Romano‡ and Hajime Tanaka†


University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

Physical and Theoretical Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road,
Oxford, OX1 3QZ, United Kingdom

One of the mysterious behaviours of pure water is its ability to withstand a large amount of
supercooling before homogeneous nucleation occurs, below which water undergoes rapid
crystallization. Why liquid water has such a large temperature range of metastability, and
what determines the slope of the homogeneous nucleation line as a function of pressure are
still key unanswered questions.
Here we propose a new scenario for water crystallization, centered on the existence of a new
metastable ice form which we call Ice 0, that provides a physical explanation for the pressure
dependence of the homogeneous nucleation line [1]. This new ice form has 99% of the
enthalpic stabilization of Ice I and is able to act as a bridge in between the latter and liquid
water, having intermediate structural features. We support our scenario with extensive
simulations and free-energy calculations of the mW water model, showing that the
homogeneous nucleation line of Ice I is parallel to the (metastable) Ice 0-liquid coexistence.
By introducing a new set of order parameters, we confirm that the formation of small Ice 0
crystals can trigger the formation of the stable Ice I phase according to Ostwald's rule of
stages.

Fig. 1: Schematic view of a crystal plane of the Ice 0 phase.
Oxygen atoms are colored in blue.
[1] J. Russo, F. Romano and H. Tanaka, Nature Mat. (accepted).

40

Water’s second glass transition
K. Amann-Winkel†, C. Gainaru‡, P.H. Handle†, M. Seidl†, H. Nelson‡, R. Böhmer‡, T.
Loerting†


Institute of Physical Chemistry, University of Innsbruck, Innrain 80-82,
6020 Innsbruck, Austria

Fakultät Physik, Technische Universität Dortmund, Otto-Hahn-Str. 4
44221 Dortmund, Germany

An understanding of the numerous anomalies of water is closely linked to an understanding
of the phase diagram of the metastable non-crystalline states of ice. The discovery of high(HDA) and low-density amorphous ice (LDA) prompted the question whether this
phenomenon of polyamorphism is connected to the occurrence of more than one supercooled
liquid phase. Alternatively, amorphous ices have been suggested to be of nanocrystalline
nature, unrelated to liquids. In case of LDA the connection to the low-density liquid (LDL) was
inferred from several experiments including the observation of a calorimetric glass-to-liquid transition
[1] at ambient pressure. However, in case of HDA instead no calorimetric signature indicating a glass
transition has been detected so far. Other experimental methods show a glass transition of HDA at
elevated pressure [2,3,4]. We present here calorimetric and dielectric measurements on LDA and
HDA, showing for the first time that HDA transforms into a liquid upon heating at ambient pressure.

Differential scanning calorimetry (DSC) is the most employed experimental method to
investigate vitrification and devitrification transitions between glasses and liquids. The glassto-liquid transition upon heating is evidenced by an endothermic step, which indicates that
the liquid has a higher heat capacity than the glass due to an increase of molecular mobility,
e.g., by unfreezing of translational motion. In the case of water, such a glass-softening
endotherm has already been observed for hyperquenched glassy water (HGW) [1] as well as
for LDA, showing a glass transition temperature Tg(LDA)=136 K (at a heating rate of 30
K/min).
Using a relaxed form of high-density amorphous ice [5,6] we demonstrate that the
glass→liquid transition HDA→HDL , is astonishingly detectable at ambient pressure. In our
measurements the corresponding calorimetric signature occurs at Tg(HDL)=116±2 K (at a
heating rate of 10 K/min). Additionally we repeatedly cycle between the ultraviscous highdensity liquid state HDL and the non-crystalline solid state HDA. The reproducibility of
switching between solid-like and liquid-like dynamics confirms the existence of an
ultraviscous high density bulk liquid at ambient pressure. [7]
The glass-to-liquid transition can also be detected by dielectric spectroscopy via the
appearance of an dielectric peak centered at about 10 –2 Hz. From the temperature dependent
peak positions a relaxation map can be constructed. The good agreement between dielectric
and calorimetric results provides a clearer picture of water's vitrification phenomenon. [7]
[1] I. Kohl, L. Bachmann, A. Hallbrucker, et al., Phys.Chem.Chem.Phys. 7, 3210 (2005).
[2] O. Mishima, J. Chem. Phys. 121, 3161 (2004)
[3] O. Andersson, Proc. Natl. Acad. Sci. U.S.A 108, 11013 (2011)
[4] M. Seidl et al., Phys. Rev. B 83, 100201/1 (2011)
[5] R. J. Nelmes, J. S. Loveday, T. Straessle, et al., Nature Physics 2, 414 (2006).
[6] K. Winkel, E. Mayer, T. Loerting, J. Phys. Chem. B 115, 14141 (2011)
[7] K. Amann-Winkel, C. Gainaru, et al., Proc. Natl. Acad. Sci. U.S.A 110, 17720 (2013)

41

Room temperature ice water films induced by surfaces:
BaF2 and CaF2 lattice mismatch.
Albert Verdaguer, Jordi Fraxedas


ICN2 - Institut Català de Nanociència i Nanotecnologia, Campus UAB, 08193, Bellaterra
(Barcelona), Spain and CSIC - Consejo Superior de Investigaciones Cientificas, ICN2 Building,
08193 Bellaterra (Barcelona), Spain

It was predicted decades ago that surfaces exhibiting hexagonal structure with surface lattice
constants close to those of the basal plane of hexagonal ice (I h) might readily induce
nucleation of ice under ambient conditions. Scientists know nowadays that this property
alone is not sufficient to predict the ice nucleation efficiency of a surface. Nevertheless, it has
been demonstrated repeatedly that surfaces whose lattice constants are close to that of ice
facilitate growth of ice in the form of hexagonal platelets and inducing the formation of
“solid-like” water layers at the interface at temperatures well above 0 oC [1]. BaF2 (111) is an
ideal surface for investigating the effects of lattice mismatch in the structures of surface water
films, because its lattice surface constant is very similar to that of I h and the results can be
compared with those obtained on CaF 2, an isostructural crystal that has similar water
adsorption energies but whose lattice constant is very different. We have studied water films
structures on BaF2 (111) and CaF2 (111) surfaces using different scanning force microscopy
(SFM) techniques and optical microscope. We observed the formation of solid-like water
films at room temperature only on BaF 2 [1], [2]. However, our results indicate that this solidlike structure must be different than I h [2]. In addition to that, our results show that that there
were important differences in how water wets both surfaces at the nanoscale, inducing
opposite wetting properties at the macroscale [4].

Figure: Structure of BaF2 and CaF2 (111) faces compared with an Ih structure. Next to the
structures wetting of the surfaces as revealed by optical microscope is shown
[1] A.Verdaguer, G.M. Sacha, H. Bluhm and M.Salmeron “Molecular structure of water at interfaces: Wetting at
the nanometer scale” Chem. Rev. 106(4), 1478-1510 (2006)
[2] A.Verdaguer, M. Cardellach, J. Fraxedas “Thin water films grown at ambient conditions on BaF 2(111)
studied by scanning polarization force microscopy” J. Chem. Phys. 129(17), 174705 (2008).
[3] A. Verdaguer, J.J. Segura, L. Lopez-Mir, G. Sauthier, J.Fraxedas “Communication: Growing room
temperature ice with graphene” J. Chem. Phys. 138, 12 (2013).
[4] M. Cardellach, A.Verdaguer*, J. Fraxedas “Defect-induced wetting on BaF 2(111) and CaF2(111) at ambient
conditions “ Surf. Sci. 605 1929-1933 (2011).

42

Glass transition and crystallization in ultrathin films of amorphous solid
water
A. Sepúlvedaa,b , M. Gonzalez-Silveiraa, C. Rodríguez-Tinocoa, M. T. Clavaguera-Moraa,
and J. Rodríguez-Viejoa,c
a

Nanomaterials and Microsystems Group, Departament de Física, Universitat Autònoma de
Barcelona, 08193 Bellaterra, Spain
b
IMEC, B-3001 Leuven, Belgium (current affiliation)
c
MATGAS Research Center, Campus, 08193 Bellaterra, Spain

The glass transition and crystallization of nanometer thick films of metastable amorphous
solid water grown by vapor deposition in an ultrahigh vacuum environment has been
investigated by means of nanocalorimetry at ultrafast heating rates. Apparent heat capacity
curves exhibit characteristic features depending on the deposition temperature. While films
grown at T ≥ 155 K are completely crystallized, those deposited at 90 K show a relaxation
exotherm prior to crystallization. Films grown between 135 and 140 K and subsequently
cooled down to 90 K reveal a clear endothermic feature before crystallization, which is
compatible with a glass-to-liquid transition. The onset temperature is located at 174 K at a
heating rate of 2.4 × 104 K/s and is independent of film thickness in the range of 16–150 nm.
Comparison of our data with other calorimetric measurements at various heating rates
suggests that water is a strong glass former in the deeply supercooled state. Crystallization
has been simulated by a nucleation-growth model which reproduces the features of the
correponding exothermic calorimetric peaks.

Figure: Effect of deposition temperature in the nanocalorimetric scans of ASW films of
similar mass (∼7.8 nmol) and thickness (∼150 nm) obtained at a scanning rate of 2.4 × 104
K/s. Curves are identified by symbols and the corresponding deposition temperature. An
enlarged view of the apparent heat capacity near glass transition for films prepared at 90 K,
120 K, and 135 K is shown in the inset.

43

Water and proton dynamics in polymer membranes for fuel cells
S. Lyonnard1,2,3, Q. Berrod1,2,3, A. Guillermo1,2,3, B. Frick4 and J. Ollivier5
1

Univ. Grenoble Alpes, INAC-SPRAM, F-38000 Grenoble, France
2
CNRS, INAC-SPRAM, F-38000 Grenoble, France
3
CEA, INAC-SPRAM, F-38000 Grenoble, France
2
Institut Laue Langevin, BP156, 6 rue J. Horowitz, 38042 Grenoble, France.

Polymer Electrolyte Membrane (PEM) Fuel cells are one of the most promising and environmental
friendly future alternative energy sources with zero pollution. These devices are generally fuelled by
hydrogen and oxygen (air) as reactants, and produce electricity by means of electrochemical reactions.
The heart of the fuel cell is a thin acidic polymer membrane which allows proton transfer from anode
to cathode, while being a barrier for electrons and gas. Proton transport and further performances of
the fuel cell are highly dependent on the hydration of the membranes. Hence, water management in
fuel cell has become a challenging issue and a microscopic understanding of proton transfer
mechanisms is a crucial step towards improving the technology.
Water plays a key role in forming the phase-separated polymer nanostructure, dissociating the
sulfonic acid groups and mediating proton transfer. Upon hydration, the ionic domains swell into an
interconnected dense H-bond network that facilitates efficient charge transfer through the electrolyte.
Proton transport arises from a complex balance between i) mass diffusion of hydronium ions and ii)
structural diffusion (Grotthuss-like ultra-fast charge transfer inside symmetric hydrated Eigen ions,
highly mediated by water molecules local reorientations). Also, peculiar surface conduction
mechanisms based on proton jumps occurring along the charged hydrophobic/hydrophilic interface
have been postulated to significantly contribute to the transport efficiency at low water content. The
various modes of proton conduction are differently balanced depending on the water content. Water
molecules are highly confined in the polymer host matrix at nanoscale, and thus significant deviations
to bulk water are found in terms of local mobility and diffusion coefficients. We have performed in
the last years a systematic Quasi-Elastic Neutron Scattering (QENS) studies on hydrated state-of-theart polymers and model surfactant systems to rationalize the structure-transport interplay and get
insights into water/proton dynamics at molecular level and ps-ns time-scale [1-5]. We showed that a
specific jump-like slow process dominates at very low hydration (λ <1.5), while, above this value,
localized translational motions and nanometric long-range diffusion are additionally observed. All the
processes are accelerated upon hydration, with steep variations of H 3O+ and H2O diffusion coefficients
observed in the early stages of swelling (λ <4). In this talk, I will present an overview of the main
QENS findings, that will be put in perspective and cross-fertilized by a comparison with the panoply
of available Numerical Simulations, NMR and Infra-red works on the same materials. A
comprehensive picture of the multi-scale proton diffusion scenario and its correlation to confined
water properties will be drawn.
[1] S. Lyonnard and G. Gebel, Neutrons for Fuel Cells Membranes: structure, sorption and transport
properties, European Physical Journal 213 (1) (2012), 195-211;
[2] S. Lyonnard, Structure and Transport Properties in Polymer Electrolyte Membranes Probed at Microscopic
Scales, Springer-Verlag, New Energies, Ed. German Antonio Ferreira, 2013.
[3] J-C. Perrin, S. Lyonnard and F. Volino; Quasielastic neutron scattering study of water dynamics in hydrated
nafion membranes, Journal of Physical Chemistry C, 111 (2007), 3393-3404.
[4] S. Lyonnard, Q. Berrod, B-A. Bruning, G. Gebel, A. Guillermo, H. Ftouni, J. Ollivier and B. Frick,
Perfluorinated surfactants as model charged systems for understanding the effect of confinement on proton
transport and water mobility in fuel cell membranes. A study by QENS., Eur. Phys. Journal Special Topics, 189
(1), 205-216 (2010).
[5] Q. Berrod, S. Lyonnard, B. Frick and J. Ollivier; Water and proton dynamics in hydrated Aquivion
membranes, submitted to J. Phys. Chem.

44

Molecular diffusion and hydrogen bond dynamics
in liquid water at high pressure
L. E. Bove1 and J. Teixeira2
1

2

IMPMC, CNRS-UMR 7590, Université Pierre & Marie Curie, 75252 Paris, France

Laboratoire Léon Brillouin (CEA/CNRS), CEA Saclay, F-91191 Gif-sur-Yvette, France

The complexity of the dynamics of liquid water results from the intermolecular potential
which is dominated by very anisotropic hydrogen bonds. A rigorous approach must analyse the
specific dynamics of hydrogen bonds which are at the origin of the unusual dependence of
molecular dynamics on external conditions, temperature and pressure.
Quasi-elastic incoherent neutron scattering, because of its sensitivity to individual
motions of hydrogen atoms, is one of the best tools to discriminate different components of
atomic and molecular motions.
Early experiments on bulk supercooled water showed that the dependence of hydrogen
bond lifetime on temperature is Arrhenius in contrast with the anomalous behaviour of
transport properties [1].
For the first time, measurements were performed at 3 GPa and 400 K, in the region of
melting of ice VII [2], using a new high pressure chamber [3]. They show: a) a strong decrease
of molecular diffusion with pressure; b) a rotational diffusion, associated to the dynamics of
hydrogen bonds, insensitive to pressure; c) the decoupling between temperature dependences
of shear viscosity and translational diffusion at high pressure, thus the breakdown of the StokesEinstein relation.
Consequently, the decoupling of molecular (translational diffusion) and hydrogen bond
(rotational diffusion) dynamics is observed also at very high pressures, a general feature
resulting from the hydrogen bond network [4]. The breakdown of SE relation implies that
extrapolation of molecular diffusion coefficients to pressures existing inside planets are not
reliable. A best alternative consists to admit that the diffusion coefficient remains constant
along the pressure melting line.
[1]

J. Teixeira, M.-C. Bellissent-Funel, S.-H. Chen and A.J. Dianoux, Phys. Rev. A 31, 1913 (1985).

[2]

L.E. Bove, S. Klotz, Th. Strässle, M. Koza, J. Teixeira and A.M. Saitta, Phys. Rev. Lett. 111, 185901

(2013).
[3]

S. Klotz, Th. Strässle and L.E. Bove, Appl. Phys. Lett. 103, 193504 (2013).

[4]

J. Teixeira, A. Luzar and S. Longeville, J. Phys.: Cond. Matter 18, S2353 (2006).

45

How to quantify structural anomaly in liquids?
Yu.D. Fomin,† V.N. Ryzhov†, E.N. Tsiok† and B. A. Klumov‡




Institute for High Pressure Physics Russian Academy of Science, 142190, Kaluzhskoe shosse 14,
Troitsk, Moscow, Russia

High Temperature Institute, Russian Academy of Sciences, 125412, Izhorskaya str. 13/2, Moscow,
Russia

It is well known that some liquids demonstrate anomalous behavior [1]. The most common
example of anomalous liquid is water [2]. Among the most discussed anomalies it is the so
called structural anomaly which means that the fluid becomes less structured under
isothermal compression. Several methods to measure the degree of structural order were
introduced in the literature and the regions of the structural anomaly were calculated by these
different methods. It was implicitly assumed that all definitions of structural order give
qualitatively identical results. However, no explicit comparison was made. This talk presents
such a comparison for the first time. We consider an example of a core-softened liquid [3,4]
and show that some of the definitions give the results which contradict to intuitive view of
liquids. Basing on this comparison we propose which definition should be used in practice.
.

[1] V. V. Brazhkin. S. V. Buldyrev, V. N. Ryzhov, and H.E. Stanley,”New Kinds of Phase
Transitions: Transformations in Disordered Substances” [Proc. NATO Advanced Research
Workshop, Volga River](Kluwer, Dordrecht, 2002).
[2] http://www1.lsbu.ac.uk/water/anmlies.html
[3] Yu. D. Fomin, N.V. Gribova, V.N. Ryzhov, S.M. Stishov and D. Frenkel, J. Chem. Phys.
129, 064512 (2008) .
[4] Yu. D. Fomin, E. N. Tsiok, and V. N. Ryzhov, Phys. Rev. E 87, 042122 (2013).

46

The Use of Distributions of Single-Molecule Properties for the Study of
Dynamic Heterogeneities in Water
Giuseppe B. Suffritti,† Pierfranco Demontis†, Marco Masia†‡ and Marco Sant†




Dipartimento di Chimica e Farmacia, Via Vienna, 2, I-07100 Sassari (Italy)

Present address: Institut für Physikalische und Theoretische Chemie, Goethe Universität
Frankfurt, Max von Laue Str. 7, D-60438 Frankfurt am Main (Germany)

The explicit trend of the distribution of two single-molecule properties (rotational relaxation
constants, mean square displacements and their cross-correlation functions of O and H atoms,
order parameters) are used to study dynamical heterogeneities in supercooled water adsorbed
in different zeolites, which are nanoporous crystalline aluminosilicates, and in bulk water.
They are evaluated from classical molecular dynamics simulations performed in the
temperature range 110-350 K, using both a special potential model developed in our
laboratory, with flexible molecules, and the TIP4P model (for bulk water).
The distributions of single-molecule properties help in following the details of the dynamical
crossover mechanisms at molecular level and confirm the previously proposed [1]
interpretation of the dynamic crossovers of supercooled bulk and nanoconfined water.
The high temperature dynamical crossover occurring in the temperature range 200-230 K can
be interpreted at a molecular level as the formation of almost translationally rigid clusters,
characterized by some rotational freedom, hydrogen bond (HB) exchange and translational
jumps as cage-to-cage processes. This process is detected also in bulk water, and corresponds
to a fragile-liquid to strong-liquid transition. However, the different trend of some
distributions for the normal liquid and for the supercooled state, where they are narrow and
regular, confirms the prevalence of a low density liquid (LDL) structure. Above the melting
point, the high density liquid (HDL) structure is present, as expected.
We also suggest a mechanism for the low temperature dynamical crossover (LTDC), falling
in the temperature range 150-185 K, and detected both experimentally and by computer
simulations in nanoconfined water.
In LTDC, adsorbed water clusters would be made of nearly rigid sub-clusters, slightly
mismatched, and thus permitting a relatively free librational motion at their borders. It
appears that the condition for LTDC to occur is the presence of highly heterogeneous
environments for the adsorbed molecules, letting some hydrogen bonds dangling or weaker
than water-water hydrogen bonds. Under these conditions some dynamics is permitted also at
very low temperature, even if most rotational motion is frozen.
[1] P. Demontis, J. Gulín-González, M. Masia, G. B. Suffritti, J. Phys. Condens. Matter 24
064110 (2012); ibid. 26, 155103 (2014).

47

Ultra-Slow Dynamics of Water in Organic Molecular Solids
E. Mitsari,† R. Macovez,*,† M. Zachariah,† P. Tripathi,† M. Romanini,†
P. Zygouri,‡ D. Gournis,‡ and J. Ll. Tamarit†


Grup de Caracterització de Materials, Departament de Física i Enginyieria Nuclear, ETSEIB,
Universitat Politècnica de Catalunya, Av. Diagonal 647, E-08028 Barcelona, Spain

Department of Material Science and Engineering, University of Ioannina, P.O. Box 1186, 45110
Ioannina, Greece

The relaxation dynamics of water in two hygroscopic molecular solids (rhodamine 6G,
C28H31N2O3Cl , and fullerol, C60(OH)24) is probed by broadband dielectric spectroscopy in the
temperature range from 200 to 450 K. Evidence is found for three types of dynamic
processes. The intermediate and the faster process is common to both probed materials. The
intermediate process stems from the reorientation of bound water molecules that are attached
directly onto organic molecules and counter-ions, and the faster one is the dynamic signature
of water molecules in higher hydration layers. All these processes are observed near room
temperature and exhibit nonmonotonic temperature dependence and decreasing spectral
strength upon heating. In fullerol a third, ultra-slow relaxation is observed at high
temperature, which may be due to the reorientation of water–fullerol complexes.

Fig1: Dielectric loss spectra of the fullerol molecule acquired upon heating from low
temperature.

[1] R. Macovez, E. Mitsari, M. Zachariah, M. Romanini, P. Zygouri, D. Gournis, J. Li.
Tamarit, J Phys Chem C 118, 4941 (2014)

48

From hydration repulsion to hydrophobic attraction:
what happens in between?
Roland R. Netz, Matej Kanduc and Emanuel Schneck
Department of Physics, Free University Berlin, Arnimallee 14, 14195 Berlin, Germany

Besides van-der-Waals and electrostatic interactions, surfaces in water experience strong
mutual solvent-induced forces. Prior research concentrated on the two limiting scenarios,
namely hydrophobic attraction (or cavitation) between hydrophobic surfaces, and hydration
repulsion for very polar (i.e. very hydrophilic) surfaces. Recent experiments demonstrated
weak attraction between mildly hydrophilic surfaces, i.e. surfaces for which the contact angle
is slightly smaller than 90 degrees, a finding that does not fit into the existing theoretical
framework.
Indeed, using atomistic simulations, we show that between the limiting well-studied regimes
representing hydrophobic attraction and hydration repulsion an intermediate novel regime
corresponding to hydrophilic attraction exists. Hydrophilic attraction occurs quite generally
for surfaces that favorably interact with water and among themselves. Analysis of the
hydrogen-bonding statistics shows that the balance between hydration repulsion and
hydrophilic attraction is dominated by surface-water hydrogen bonds. The adhesive contact
angle that determines the transition between attraction and repulsion lies in the range between
60 and 80 degrees, this not only agrees with experiments but also constitutes a very important
and for practical applications relevant range of surface contact angles.

49



Parole chiave correlate