Implementation of a time-dependent multiconfiguration self-consistent-field method for coupled electron-nuclear dynamics in diatomic molecules driven by intense laser pulses

TL;DR

This paper introduces a comprehensive time-dependent multiconfiguration self-consistent-field method for simulating coupled electron-nuclear dynamics in diatomic molecules under intense laser pulses, capturing full electronic motion without the Born-Oppenheimer approximation.

Contribution

The implementation allows for full-dimensional electronic motion and coupled electron-nuclear dynamics without relying on the Born-Oppenheimer approximation in diatomic molecules.

Findings

Applied to hydrogen molecule for high-harmonic generation

Analyzed electron-nuclear correlation effects

Demonstrated method's capability in strong-field dynamics

Abstract

We present an implementation of a time-dependent multiconfiguration self-consistent-field (TD-MCSCF) method [R. Anzaki et al., Phys. Chem. Chem. Phys. 19, 22008 (2017)] with the full configuration interaction expansion for coupled electron-nuclear dynamics in diatomic molecules subject to a strong laser field. In this method, the total wave function is expressed as a superposition of different configurations constructed from time-dependent electronic Slater determinants and time-dependent orthonormal nuclear basis functions. The primitive basis functions of nuclei and electrons are strictly independent of each other without invoking the Born-Oppenheimer approximation. Our implementation treats the electronic motion in its full dimensionality on curvilinear coordinates, while the nuclear wave function is propagated on a one-dimensional stretching coordinate with rotational nuclear motion neglected. We apply the present implementation to high-harmonic generation and dissociative ionization of a hydrogen molecule and discuss the role of electron-nuclear correlation.