Effects of core space and excitation levels on ground-state correlation and photoionization dynamics of Be and Ne

TL;DR

This study investigates how core space and excitation levels influence ground-state correlation energies and photoionization dynamics in Be and Ne, using advanced computational methods to analyze correlation effects and their impact on photoelectron spectra.

Contribution

It systematically compares correlation energies and entanglement measures across different excitation schemes and active spaces, highlighting the role of a dynamic core in photoionization.

Findings

Correlation energy magnitude does not always correlate with entanglement measures.

Including a dynamic core significantly affects photoelectron spectra.

Different excitation schemes impact the accuracy of ground-state and ionization dynamics.

Abstract

We explore the effects of correlation on the ground-state energies and on photoionization dynamics in atomic Be and Ne. We apply the time-dependent restricted-active-space self-consistent-field method for several excitation schemes and active orbital spaces with and without a dynamic core to address the effects systematically at different levels of approximation. For the ground-state many-electron wave functions, we compare the correlation energies with entropic measures of entanglement. A larger magnitude of the correlation energy does not always correspond to a larger value of the considered entanglement measures. To evaluate the impact of correlation in a process involving continua, we consider photoionization by attosecond pulses. The photoelecton spectra may be significantly affected by including a dynamical core.