Improved semiclassical dynamics through adiabatic switching trajectory sampling

TL;DR

This paper presents an enhanced semiclassical dynamics method for quantum vibrational spectroscopy that reduces chaotic trajectories and improves accuracy by adiabatically switching from harmonic to actual potentials.

Contribution

It introduces a novel phase space sampling technique that transitions from harmonic to real potentials, decreasing chaotic trajectories and enhancing semiclassical calculation precision.

Findings

Reduces the number of chaotic trajectories needed.

Improves accuracy and precision of vibrational spectra.

Applicable to systems with varying degrees of chaos.

Abstract

We introduce an improved semiclassical dynamics approach to quantum vibrational spectroscopy. In this method, a harmonic-based phase space sampling is preliminarily driven toward non-harmonic quantization by slowly switching on the actual potential. The new coordinates and momenta serve as initial conditions for the semiclassical dynamics calculation, leading to a substantial decrease in the number of chaotic trajectories to deal with. Applications are presented for model and molecular systems of increasing dimensionality characterized by moderate or high chaoticity. They include a bidimensional Henon-Heiles potential, water, formaldehyde, and methane.The method improves accuracy and precision of semiclassical results and it can be easily interfaced with all pre-existing semiclassical theories.