Structural Properties of Liquid Water and Ice Ih from Ab-Initio Molecular Dynamics with a Non-Local Correlation Functional

Equilibrium Born-Oppenheimer molecular dynamics simulations have been performed in the canonical ensemble to investigate the structural properties of liquid water and ice Ih (hexagonal ice) at 298 and 273 K, respectively, using a state-of-the-art non-local correlation functional, whilst size effects have been examined explicitly in the case of liquid water. This has led to improved agreement with experiments for pair distribution functions, in addition to molecular dipole moments, vis-a-vis previous flavours of ab-initio molecular dynamics simulation of water, highlighting the importance of appropriate dispersion. Intramolecular geometry has also been examined, in addition to hydrogen-bonding interactions; it was found that an improved description of dispersion via non-local correlation helps to reduce over-structuring associated with the Perdew-Becke-Ernzerhof (PBE) and other commonly-used functionals.