Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire (LIONS)
CEA/SACLAY, 91191-Gif-sur-Yvette Cedex, France+33 1 69 08 48 18
+33 1 69 08 66 40
Research scientist, directeur de recherche, expert international
Theoretician in condensed matter, in statistical mechanics of charged liquids
Understanding the thermodynamical, equilibrium, structural and stability properties of aqueous solutions containing charged objects of various geometries and shapes (ions, organic or mineral oxide colloids, latex, proteins, DNA, semi-flexible polyelectrolytes, clays,...) from the correlations between particles at the nanometer level. Quantitatively explaining the experimental data in small angle scattering, reflectivity, osmotic pressure,...
More recently, analysis at the explicit level of description of the solvent (mainly water) molecules in bulk and around solute particles with classical force fields.
Liquid physics techniques: Integral equations, DFT, Monte Carlo and Molecular Dynamics simulations in various ensembles,...
1) Molecular Integral equations: solve Ornstein-Zernike (OZ) equation with approximate closure (mainly HNC which neglects the bridge function) for the pair correlation functions g(r,Ω) where r is the distance between the centers of mass (the oxygen atoms for H2O solvent) and Ω is the relative orientation between the two molecules (five Euler angles). The resolution benefits from the powerful use of projections g_mnl_μν(r) onto rotational invariants (generalysed spherical harmonics) which are characterized by five indices and depend on the separation r only. Very efficient homemade codes make it possible to solve the numerical problem in a few minutes for bulk water, bulk electrolytes, isolated solute of "simple" shape immersed in water...
2) Monte Carlo (MC) and Molecular Dynamics (MD) simulations: The trajectories of bulk systems (pure water, electrolytes...) are analysed in terms of projections g_mnl_μν(r). The simulation data available at short distances r only are then combined with the HNC closure valid at least at long distances and the OZ+Integral equation problem is solved. The overwhole picture enables first to clean the bare simulation data from the explicit+implicit finite-size corrections in a self-consistent manner and then to provide all exact pair correlations (total, direct, cavity, bridge) at all distances r and/or all scattering vectors q. A new original technique investigates Grand Canonical Monte Carlo simulations where the insertion/destruction of molecules is performed via a trial non-equilibrium MD trajectory trough the 4th dimension.
3) 3D Molecular DFT: A solute is immersed in a bulk solvent and one minimizes the solvent functional in order to reach the solvent profile (3D x,y,z vector + 3 Euler angles orientation) around the solute and the solvation free energy of the solute. For instance, the approximate functional involves only the pair direct correlation function of the bulk (provided by the previous techniques 1-2), which corresponds using the HNC approximation for the solute-solvent correlations at infinite dilution of the solute component. Again, the original use of projections for the angular dependence of the solvent profile makes it possible to solve the MDFT problem in a few minutes for any molecular or even macromolecular solute of any complex shape.
The near future (2019) consists to add approximate solute-solvent bridge function/functional in order to go beyond the HNC approximation.
A review on colloidal interactions:
L. Belloni, J. Phys. : Cond. Matter 12, R549 (2000)
Some recent publications:
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Volume: 134 Issue: 8 Pages: 3780-3786 Published: FEB 29 2012
JOURNAL OF CHEMICAL PHYSICS Volume: 136 Issue: 15 Article Number: 154503 Published: APR 21 2012
PHYSICAL REVIEW LETTERS Volume: 108 Issue: 20 Article Number: 206102 Published: MAY 15 2012
LANGMUIR Volume: 28 Issue: 31 Pages: 11575-11583 Published: AUG 7 2012
JOURNAL OF PHYSICAL CHEMISTRY C Volume: 116 Issue: 51 Pages: 26841-26849 Published: DEC 27 2012
CHEMICAL COMMUNICATIONS Volume: 49 Issue: 96 Pages: 11284-11286 Published: 2013
MOLECULAR PHYSICS Volume: 112 Issue: 9-10 Pages: 1246-1256 Published: MAY 19 2014
COLLOID AND POLYMER SCIENCE Volume: 293 Issue: 1 Pages: 1-22 Published: JAN 2015
NANOSCALE Volume: 8 Issue: 10 Pages: 5454-5469 Published: 2016
PHYSICAL CHEMISTRY CHEMICAL PHYSICS Volume: 19 Issue: 1 Pages: 167-174 Published: JAN 7 2017
APPLIED CLAY SCIENCE Volume: 141 Pages: 308-315 Published: JUN 2017
JOURNAL OF CHEMICAL PHYSICS Volume: 147 Issue: 9 Article Number: 094107 Published: SEP 7 2017
JOURNAL OF CHEMICAL PHYSICS Volume: 147 Issue: 16 Article Number: 164121 Published: OCT 28 2017
JOURNAL OF CHEMICAL PHYSICS Volume: 147 Issue: 22 Article Number: 224110 Published: DEC 14 2017
JOURNAL OF PHYSICAL CHEMISTRY LETTERS Volume: 9 Issue: 8 Pages: 1985-1989 Published: APR 19 2018
JOURNAL OF PHYSICAL CHEMISTRY LETTERS Volume: 9 Issue: 13 Pages: 3698-3702 Published: JUL 5 2018
JOURNAL OF CHEMICAL PHYSICS Volume: 149 Issue: 9 Article Number: 094111 Published: SEP 7 2018
104. Non-equilibrium Hybrid Insertion/Extraction through the 4th Dimension in Grand-Canonical Simulation