Year: 2011
Type: article
Abstract: It is known that ab initio molecular dynamics (AIMD) simulations of liquid water at ambient conditions, based on the generalized gradient approximation (GGA) to density functional theory (DFT), with commonly used functionals fail to produce structural and diffusive properties in reasonable agreement with experiment. This is true for canonical, constant temperature simulations where the density of the liquid is fixed to the experimental density. The equilibrium density, at ambient conditions, of DFT water has recently been shown by Schmidt et al. [J. Phys. Chem. B, 113, 11959 (2009)] to be underestimated by different GGA functionals for exchange and correlation, and corrected by the addition of interatomic pair potentials to describe van der Waals (vdW) interactions. In this contribution we present a DFT-AIMD study of liquid water using several GGA functionals as well as the van der Waals density functional (vdW-DF) of Dion et al. [Phys. Rev. Lett. 92, 246401 (2004)]. As expected, we find that the density of water is grossly underestimated by GGA functionals. When a vdW-DF is used, the density improves drastically and the experimental diffusivity is reproduced without the need of thermal corrections. We analyze the origin of the density differences between all the functionals. We show that the vdW-DF increases the population of non-H-bonded interstitial sites, at distances between the first and second coordination shells. However, it excessively weakens the H-bond network, collapsing the second coordination shell. This structural problem is partially associated to the choice of GGA exchange in the vdW-DF. We show that a different choice for the exchange functional is enough to achieve an overall improvement both in structure and diffusivity.
Source: The Journal of Chemical Physics
DOI: 10.1063/1.3521268
Authors: Jue Wang, G. Román-Pérez, Jose M. Soler, Emilio Artacho, M.-V. Fernández-Serra
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: QUANTUM THEORY OF SEMICONDUCTOR PHOTO-CATALYSIS AND SOLAR WATER SPLITTING, G132563423, G1572106353, G222768804, QUANTUM THEORY OF SEMICONDUCTOR PHOTO CATALYSIS AND SOLAR WATER SPLITTING, G338944111, G5292656900, TAS::89 0227::TAS RECOVERY;NEW-EARLY CAREER:RECOVERY ACT- FIRST PRINCIPLES MODELING OF METAL-ELECTROLYTE SYSTEMS: A NOVEL APPROACH TO THE STUDY OF TH, G7748514026
OpenAlex ID: W1984955642