Ab-Initio calculation of the autoionization product of water using path integral molecular dynamics

Thomsen, B.  ; 志賀 基之   

Thomsen, B.; Shiga, Motoyuki

The autoionization constant (pKw) of water is the most fundamental part of conventional acid-base chemistry and it has been the subject of countless studies, the nuclear quantum effects (NQEs) on this fundamental property have however not previously been studied. In this study we use coordination number (CN) constrained molecule dynamics (MD) and path integral MD (PIMD) to calculate the pKw of water and its isotopologs. The potential energy of water was here described by either an empirical forcefield (OSS2), semi-empirical tight binding density functional theory (DFTB) or ab-initio density functional theory (DFT).