Elucidating the role of many-body forces in liquid water. I. Simulations of water clusters on the VRT(ASP-W) potential surfaces

Publisher Website
Google Scholar
Abstract
We test two new potentials for water, fit to vibration-rotation tunneling (VRT) data by employing diffusionquantum Monte Carlo simulations to calculate the vibrational ground-state properties of water clusters. These potentials, VRT(ASP-W)II and VRT(ASP-W)III, are fits of the highly detailed ASP-W (anisotropic site potential with Woermer dispersion)ab initio potential to ( D 2 O ) 2 microwave and far-infrared data, and along with the SAPT 5s (five-site symmetry adapted perturbation theory) potentials, are the most accurate water dimer potential surfaces in the literature. The results from VRT(ASP-W)II and III are compared to those from the original ASP-W potential, the SAPT 5s family of potentials, and several bulk water potentials. Only VRT(ASP-W)III and the spectroscopically “tuned” SAPT 5st (with N-body induction included) accurately reproduce the vibrational ground-state structures of water clusters up to the hexamer. Finally, the importance of many-body induction and three-body dispersion are examined, and it is shown that the latter can have significant effects on water cluster properties despite its small magnitude.