Photoelectron spectra calculated from absorption

We demonstrate a way to calculate photoelectron spectra on a numerical domain much smaller than the actual extension of the wave function. Specifically, a hydrogen atom exposed to a laser pulse in the moderately ultraviolet region is studied numerically within the dipole approximation. Outgoing waves are absorbed by means of a complex absorbing potential. The corresponding photoelectron spectra are calculated by aggregating the absorbed part of the outgoing particle. Via a density operator formulation and projections onto time-independent scattering states, we obtain convergent spectra using numerical domains for which a significant part of the unbound wave is absorbed during interaction with the time-dependent field. We compare this numerical approach with methods based on approximating time-dependent scattering states by Volkov states, which do not encompass the long-range nature of the Coulomb potential. This comparison demonstrates how the present method, which was introduced by Selst\o{} [Phys. Rev. A 106, 042213 (2022)], is able to account for Coulomb corrections to the photoelectron spectra.