Time-Dependent B-Spline R-Matrix Approach to Double Ionization of Atoms by XUV Laser Pulses

TL;DR

This paper introduces a non-perturbative, ab initio time-dependent B-Spline R-Matrix approach to accurately simulate double ionization of atoms by intense XUV laser pulses, enabling detailed analysis of electron dynamics.

Contribution

The paper develops a novel time-dependent B-Spline R-Matrix method combined with Arnoldi-Lanczos propagation for studying double ionization under intense XUV pulses, extending previous static and perturbative techniques.

Findings

Accurate double ionization results for helium agree with benchmark data.

The method successfully models two-color pump-probe processes.

Electron energy and momentum distributions are obtained for complex ionization scenarios.

Abstract

We present an {\it ab initio} and non-perturbative time-dependent approach to the problem of double ionization of a general atom driven by intense XUV laser pulses. After using a highly flexible $B$-Spline $R$-matrix method to generate field-free Hamiltonian and electric dipole matrices, the initial state is propagated in time using an efficient Arnoldi-Lanczos scheme. Test calculations for double ionization of He by a single laser pulse yield good agreement with benchmark results obtained with other methods. The method is then applied to two-color pump-probe processes, for which momentum and energy distributions of the two outgoing electrons are presented.