Path integral simulations

Shiga, Motoyuki

Reference Module in Chemistry, Molecular Sciences and Chemical Engineering (Internet), 22 Pages, 2018/00

https://doi.org/10.1016/B978-0-12-409547-2.11614-2

Nuclear quantum effects are important in molecular systems containing light elements such as hydrogen. For example large zero vibration and proton tunneling in hydrogen bonded systems originate from nuclear quantum effects. We herein describe path integral molecular dynamics (PIMD) where nuclear quantum effects are taken into account based on imaginary time path integral theory. PIMD provides numerically exact solutions for quantum statistics of complex molecular systems in thermal equilibrium. Centroid and ring polymer molecular dynamics are extensions to provide approximate quantum dynamics. Combination with ab initio electronic structure calculations enables simulation of the whole entity of many-electron many-nuclei systems.