First-principles molecular dynamics simulations of supercritical water: the importance of dispersion corrections
Ari Paavo Seitsonen
Kohn-Sham density functional theory, with local density approximation or present-day generalized gradient approximation exchange-correlation functionals, either gives sporadic results or fails completely to account for London dispersion forces. In the case of water, this results in an overestimated melting temperature and an overstructured liquid in the simulations.
Considerable efforts have been made to address this shortfall and several proposals have been made in the literature, such as the dispersion-corrected atom-centered potentials (DCACP) [1] or the empirical Grimme corrections [2].
The effect of such corrections have been adressed recently in ambient water [3,4] and it has been found that they largely correct for the previous shortfalls. The importance of dispersion corrections is expected to be even larger at low densities as in supercritical water.
We have performed first-principles molecular dynamic simulations of water at densities of 1. (ambient) and 0.7 g.cm-3 (supercritical) at different temperatures. We shall present the effect of dispersion corrections on the structural and dynamical properties.
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