Structural, Electronic, and Dynamical Properties of Liquid Water by ab initio Molecular Dynamics based on SCAN Functional within the Canonical Ensemble

TL;DR

This study uses ab initio molecular dynamics with the SCAN functional to accurately simulate liquid water's properties, showing improvements over previous functionals in capturing key structural and electronic features.

Contribution

It demonstrates that the SCAN functional provides a more accurate and reliable description of liquid water's properties in AIMD simulations compared to PBE and PBE+vdW methods.

Findings

SCAN captures intermediate-range vdW interactions effectively.

SCAN reduces overestimated hydrogen bonding in simulations.

Results are consistent across canonical and isothermal-isobaric ensembles.

Abstract

We perform ab initio molecular dynamics (AIMD) simulation of liquid water in the canonical ensemble at ambient conditions using the SCAN meta-GGA functional approximation, and carry out systematic comparisons with the results obtained from the GGA-level PBE functional, and Tkatchenko-Scheffler van der Waals (vdW) dispersion correction inclusive PBE functional. We analyze various properties of liquid water including radial distribution functions, oxygen-oxygen-oxygen triplet angular distribution, tetrahedrality, hydrogen bonds, diffusion coefficients, ring statistics, density of states, band gaps, and dipole moments. We find that the SCAN functional is generally more accurate than the other two functionals for liquid water by not only capturing the intermediate-range vdW interactions but also mitigating the overly strong hydrogen bonds prescribed in PBE simulations. We also compare the results of SCAN-based AIMD simulations in the canonical and isothermal-isobaric ensembles. Our results suggest that SCAN provides a reliable description for most structural, electronic, and dynamical properties in liquid water.