Strong field ionization and gauge dependence of nonlocal potentials

TL;DR

This paper investigates the gauge dependence of nonlocal potential models in strong field ionization, finding that the length gauge is generally preferable for accurate modeling of photoionization phenomena.

Contribution

It provides a comparative analysis of length and velocity gauges in nonlocal potential models, highlighting the gauge that yields more consistent results.

Findings

Length gauge is preferable for a wide range of parameters.

Nonlocal potential models break electromagnetic gauge invariance.

Gauge choice affects the accuracy of ionization predictions.

Abstract

Nonlocal potential models have been used in place of the Coulomb potential in the Schrodinger equation as an efficient means of exploring high field laser-atom interaction in previous works. Al- though these models have found use in modeling phenomena including photo-ionization and ejected electron momentum spectra, they are known to break electromagnetic gauge invariance. This paper examines if there is a preferred gauge for the linear field response and photoionization characteristics of nonlocal atomic binding potentials in the length and velocity gauges. It is found that the length gauge is preferable for a wide range of parameters.