Role of van der Waals corrections in first principles simulations of alkali metal ions in aqueous solutions

Ikeda, Takashi; Boero, M.*

By resorting to a novel implementation of the first-principles-based van der Waals correction based on maximally localized Wannier functions, we inspect its performance and assess its reliability for aqueous solutions of alkali metal ions. We find that van der Waals interactions, when added to the widely used revPBE gradient corrected functional, influence substantially both structural and dynamical properties of water molecules, with particular emphasis on the hydration shell of the alkali cations. These effects are more evident for strong structure-making and -breaking cationic species. Moreover, self-diffusion coefficients and reorientation correlation times of solvating water molecules change systematically, showing a trend in better agreement with experiments with respect to simulations neglecting the long-range dispersion contributions.