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

Abstract

By resorting to a novel implementation of the first-principles-based van der Waals correction (vdWC) based on maximally localized Wannier functions (MLWFs), we inspect its performance and assess its reliability for aqueous solutions of alkali metal ions. In our implementation of vdWCs, an efficient extrapolation scheme is introduced to allow for affordable first principles molecular dynamics avoiding the explicit recalculation of MLWFs at each step. We find that vdWCs, 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.

Sensitivity to Dispersion Forces in First-Principles Modeling of Disordered Chalcogenides

“…Keeping in mind that the DFT-D2 formula proposed by Grimme (2006) was employed in a recent investigation (Bouzid et al, 2015b), we turn to an alternative recipe (vdW W ) for comparative purposes. It is appropriate in this context to recall the main foundations of this scheme, by referring the reader for details to the original papers thoroughly illustrating this formalism and the connections with the concept of maximally localized Wannier functions (MLWFs) (Wannier, 1937;Silvestrelli et al, 1998;Ikeda and Boero, 2015). Accordingly, one writes the vdW interaction in the standard way (Andersson et al, 1996), namely:…”

Absolute proton hydration free energy, surface potential of water, and redox potential of the hydrogen electrode from first principles: QM/MM MD free-energy simulations of sodium and potassium hydration

“…For the cluster-continuum calculations, error sources include the selection of the clusters (sampling), their small sizes (smooth trends and fast convergence being required for a meaningful extrapolation 117 ), the estimation of the cluster entropy, 118-120 the choice of a cluster permittivity in the CE calculation, and the problems associated with a QM-CE boundary (surface definition, atomic radii). For the CPMD/BOMD calculations, error sources include the shortcomings of DFT methods in terms of electron correlation (including dispersion), affecting both bulk water properties [121][122][123][124][125][126][127][128][129][130] and ion-water interactions, 66,67,105,131 the small system sizes considered (resulting in a high weight for the approximate finite-size correction term), the very limited sampling times, the ambiguity in defining the appropriate reference potential within DFT water, 21,112,[132][133][134][135][136] and the numerical problems (see, e.g., footnotes 42 and 45 in Ref. 111) associated with creating a species or injecting electrons when applying computational alchemy in a QM framework [137][138][139][140][141][142][143] (see, however, Refs.…”

Atomic Structure of Glassy GeTe4 as a Playground to Assess the Performances of Density Functional Schemes Accounting for Dispersion Forces

“…Accordingly, in Ref. 10, we focused on the comparison between distinct sets of BLYP data, namely the two already available (not including dispersion forces, named NovdW and adopting the D2-Grimme scheme, named vdW G ) and a third one, making use of the maximally localized Wannier functions (MLWF) framework (vdW W hereafter), known for exploiting the evolution of the electronic structure when updating the dispersion coefficients [12][13][14][15] . Taken altogether, the results obtained did not provide unambiguous indications.…”