Nonsequential double ionization with time-dependent renormalized-natural-orbital theory

TL;DR

This paper tests the new time-dependent renormalized natural orbital theory (TDRNOT) on a model of non-sequential double ionization, showing it effectively captures complex electron dynamics with minimal natural orbitals, thus validating its potential for strong-field physics.

Contribution

The paper demonstrates that TDRNOT accurately reproduces non-sequential double ionization phenomena using only ten natural orbitals per spin, highlighting its efficiency and effectiveness.

Findings

TDRNOT reproduces the NSDI 'knee' with minimal orbitals.

Correlated spectra require more natural orbitals for accuracy.

TDRNOT is validated as a promising method for strong-field electron dynamics.

Abstract

Recently introduced time-dependent renormalized natural orbital theory (TDRNOT) is tested on non-sequential double ionization (NSDI) of a numerically exactly solvable one-dimensional model He atom subject to few-cycle, 800-nm laser pulses. NSDI of atoms in strong laser fields is a prime example of non-perturbative, highly correlated electron dynamics. As such, NSDI is an important "worst-case" benchmark for any time-dependent few and many-body technique beyond linear response. It is found that TDRNOT reproduces the celebrated NSDI "knee," i.e., a many-order-of-magnitude enhancement of the double ionization yield (as compared to purely sequential ionization) with only the ten most significant natural orbitals (NOs) per spin. Correlated photoelectron spectra - as "more differential" observables - require more NOs.