Dyson Orbitals within the fc-CVS-EOM-CCSD Framework

We report on the implementation and illustrative applications of Dyson orbitals within the recently proposed frozen-core (fc) core-valence separated (CVS) equation-of-motion (EOM) coupled-cluster singles and doubles (CCSD) method, which enables efficient and accurate characterization of core-ionized states. Dyson orbitals are reduced quantities that can be interpreted as correlated states of the ejected/attached electron.
Dyson orbitals enter the expressions of various experimental observables, such as photoionization cross sections; thus, they are necessary for modeling photoelectron spectra.
Here we discuss the simulations of X-ray photoelectron spectra (XPS) and propose an approach to simulate time-resolved (TR-)XPS for probing excited states.
As illustrative examples, we present the simulation of the XPS of the ground state of adenine and of TR-XPS of the excited states of uracil.