Towards automated multi-dimensional quantum dynamical investigations of double-minimum potentials: Principles and example applications

Abstract

A multi-coordinate expansion of potential energy surfaces has been used to perform quantum dynamical calculations for reactions showing double-minimum potentials. Starting from the transition state, a fully automated algorithm for exploring the multi-dimensional potential energy surface represented by arbitrary internal or normal coordinates allows for an accurate description of the relevant regions for vibrational dynamics calculations. An interface to our multi-purpose quantum-dynamics program M rP ropa enables routine calculations for simple chemical reactions. Illustrative calculations involving potential energy surfaces obtained from explicitly-correlated coupled-cluster calculations, CCSD(T)-F12a, are provided for the tunneling splittings in the isotopologues of hydrogen peroxide and for reaction dynamics based on the enantiomeric inversion of PHDCl.