Time-dependent renormalized-natural-orbital theory applied to laser-driven H$_2^+$

TL;DR

This paper extends time-dependent renormalized-natural orbital theory (TDRNOT) to include nuclear motion in H$_2^+$, enabling accurate modeling beyond the Born-Oppenheimer approximation and capturing complex laser-driven dynamics.

Contribution

The authors develop a multi-component TDRNOT framework that incorporates electronic and nuclear natural orbitals, deriving exact equations of motion for improved simulation of molecular systems.

Findings

TDRNOT accurately reproduces exact Schrödinger equation results for H$_2^+$.

The method successfully models ground state, spectra, fragmentation, and high-order harmonic generation.

Benchmarking shows TDRNOT's potential for complex molecular dynamics simulations.

Abstract

Recently introduced time-dependent renormalized-natural orbital theory (TDRNOT) is extended towards a multi-component approach in order to describe H$_2^+$ beyond the Born-Oppenheimer approximation. Two kinds of natural orbitals, describing the electronic and the nuclear degrees of freedom are introduced, and the exact equations of motion for them are derived. The theory is benchmarked by comparing numerically exact results of the time-dependent Schr\"odinger equation for a H$_2^+$ model system with the corresponding TDRNOT predictions. Ground state properties, linear response spectra, fragmentation, and high-order harmonic generation are investigated.