Université Paul Sabatier - Bat. 3R1b4 - 118 route de Narbonne 31062 Toulouse Cedex 09, France

Accueil > Séminaires > 2016

How to design accurate classical force-fields to model hydration of highly charged heavy ions : from the gas phase to the bulk ?

Valérie Vallet, PhLAM (Université de Lille)

Salle 20 RdC, Jeudi 09 Juin, 14h - 15h

A detailed description of a metal-ion’s coordination environment, specifically its coordinating ligands, their numbers and their distances, is a necessary prerequisite to the development of a predictive understanding of its physical and chemical behavior in aqueous solution. At the core of this chemistry is the understanding of how a specific configuration around the metal ion takes place, and how the other solution components, including other dissolved metal ions, counter ions, and the solvent, influence the structure and dynamics of the targeted species.

In this seminar, we will discuss the various stages of the development of an accurate and predictive theoretical model that can reveal which interactions drive the molecular-level structure and dynamics and against whom solvent molecules and counter ions compete. The classical force-field we use to describe all interactions present in a water solution (water-water, metal-water, water-counter-ions, metal-counter ions) is more sophisticated than common polarizable force-fields as it accounts for all the subtle many-body interactions taking place in a solute-solvent-anion system, including hydrogen bonding and covalent interactions, the latter of which are represented in the form of a charge-transfer term. The force-field parameters are adjusted to reproduce highly accurate quantum chemical data on representative hydrated clusters.

We will discuss the results of MD trajectories obtained for bulk water, halide counter-ions and the thorium(IV) aqua in the light of EXAFS and HEXS experimental data acquired by Argonne National Lab’s Heavy Element group.

1) F. Réal, M. Trumm, B. Schimmelpfennig, M. Masella and V. Vallet, J. Comput. Chem., 2013, 34, 707–719.
2) F. Réal, V. Vallet, J.-P. Flament and M. Masella, J. Chem. Phys., 2013, 139, 114502.
3) F. Réal, A. S. P. Gomes, Y. O. Guerrero Martínez, T. Ayed, N. Galland, M. Masella and V. Vallet, J. Chem. Phys., 2016, 144, 124513.