Lanthanoids(III) and actinoids(III) in water : diffusion coefficients and hydration enthalpies from polarizable molecular dynamics simulations

Fausto Martelli (1) , Sacha Abadie (1) , J.-P. Simonin (2) , Rodolphe Vuilleumier (3) , Riccardo Spezia (1)

1 LAMBE - Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement
2 PECSA - Physicochimie des Electrolytes, Colloïdes et Sciences Analytiques
3 PASTEUR - Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640)

By using polarizable molecular dynamics (MD) simulations of lanthanoid(III) and actinoid(III) ions in water, we obtained ionic diffusion coefficients and hydration enthalpies for both series. These values are in good agreement with experiments. Simulations thus allow us to relate them to microscopic structure. In particular, across the series the diffusion coefficients decrease, reflecting the increase of ion-water interaction. Hydration enthalpies also show that interactions increase from light to heavy ions in agreement with experiment. The apparent contradictory result of the decrease of the diffusion coefficient with decreasing ionic radius is tentatively explained in terms of dielectric friction predominance on Stokes' diffusive regime.

Mots clés: Dielectric friction; Diffusive regime; Hydration enthalpy; Ion-water interactions; Ionic radius; Lanthanoids; Microscopic structures; Molecular dynamics simulations; Actinides; Enthalpy; Experiments; Hydration; Molecular dynamics; Rare earth elements; Thermodynamics; Water; Diffusion

Domaines: Chimie-Physique [physics.chem-ph]

Fausto Martelli, Sacha Abadie, J.-P. Simonin, Rodolphe Vuilleumier, Riccardo Spezia. Lanthanoids(III) and actinoids(III) in water : diffusion coefficients and hydration enthalpies from polarizable molecular dynamics simulations. Pure and Applied Chemistry, 2013, 85 (1), pp.237-246. ⟨10.1351/PAC-CON-12-02-08⟩. ⟨hal-00797819⟩