Photoelectron spectra with Qprop and t-SURFF

TL;DR

This paper presents an implementation of the t-SURFF method within the Qprop solver to efficiently compute momentum-resolved photoelectron spectra from the time-dependent Schrödinger equation, especially for challenging long-wavelength or long-pulse regimes.

Contribution

The integration of t-SURFF into Qprop enables efficient PES calculations without large numerical grids, improving computational feasibility for complex strong-field simulations.

Findings

Efficient PES calculation in long-wavelength regimes.

Reduced computational resources due to smaller numerical grids.

Successful implementation in a widely used TDSE solver.

Abstract

Calculating strong-field, momentum-resolved photoelectron spectra (PES) from numerical solutions of the time-dependent Schr\"odinger equation (TDSE) is a very demanding task due to the large spatial excursions and drifts of electrons in intense laser fields. The time-dependent surface flux (t-SURFF) method for the calculation of PES [L. Tao, A. Scrinzi, New Journal of Physics 14, 013021 (2012)] allows to keep the numerical grid much smaller than the space over which the wavefunction would be spread at the end of the laser pulse. We present an implementation of the t-SURFF method in the well established TDSE-solver Qprop [D. Bauer, P. Koval, Comput. Phys. Commun. 174, 396 (2006)]. Qprop efficiently propagates wavefunctions for single-active electron systems with spherically symmetric binding potentials in classical, linearly (along $z$) or elliptically (in the $xy$-plane) polarized laser fields in dipole approximation. Its combination with t-SURFF makes the simulation of PES feasible in cases where it is just too expensive to keep the entire wavefunction on the numerical grid, e.g., in the long-wavelength or long-pulse regime.