Capturing Correlation Effects on Photoionization Dynamics

Abstract

A highly correlated combination of the equation-of-motion coupled cluster (EOM-CC) Dyson orbital and the multicentric B-spline time-dependent density functional theory (TDDFT)-based approach is proposed and implemented within the single-channel approximation to describe molecular photoionization processes. The twofold objective of the approach is to capture interchannel coupling effects, missing in the B-spline DFT treatment, and to explore the response of Dyson orbitals to strong correlation effects and its influence on the photoionization observables. We validate our scheme by computing partial cross sections, branching ratios, asymmetry parameters, and molecular frame photoelectron angular distributions of simple molecules. Finally, the method has been applied to the study of photoelectron spectra of the Ni­(C3H5)2 molecule, where giant correlation effects completely destroy the Koopmans picture.

Photoelectron Circular Dichroism as a Probe of Chiral Hydrocarbons

“…It must be reminded that several refinements are already possible with respect to the pure DFT approach presented in this exploratory study [24][25][26], although the features examined are so clear and strong that we believe are realistically described. More work in the development of theoretical approaches is needed, as already mentioned, to capture finer details, and especially to describe the first few eV after threshold.…”

Photoionization Observables from Multi-Reference Dyson Orbitals Coupled to B-Spline DFT and TD-DFT Continuum

“…The computational approach for the electronic continuum at the DFT and TD-DFT level, and the coupling to Dyson orbitals to obtain photoionization observables has been presented in detail in recent works [18,19,23,36], so we summarize here the most important points.…”

“…where φ d IF is the Dyson orbital relative to the initial and final states of interest previously defined [36]. With respect to DFT, TD-DFT includes channel coupling at the level of single-excitation configuration interaction, and some ground state correlation.…”

Multi-reference approach to the computation of double core-hole spectra

“…In analogy with the Dyson orbital formulation for single ionization, 63,64 the full dipole element in Eq. ( 2) can be approximated by the term involving a dipole transition between a two-particle Dyson function, defined by the amplitudes…”