Equation-of-Motion Coupled-Cluster Theory to Model L-Edge X-ray Absorption and Photoelectron Spectra
Marta L. Vidal, Pavel Pokhilko, Anna I. Krylov, Sonia Coriani
Abstract
We present an extension of the equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) theory for computing X-ray L-edge spectra, both in the absorption (XAS) and in the photoelectron (XPS) regimes. The approach is based on the perturbative evaluation of spin-orbit couplings using the Breit-Pauli Hamiltonian and nonrelativistic wave functions described by the fc-CVS-EOM-CCSD ansatz (EOM-CCSD within the frozen-core core-valence separated (fc-CVS) scheme). The formalism is based on spinless one-particle density matrices. The approach is illustrated by modeling XAS and XPS of several model systems ranging from Ar to small molecules containing sulfur and silicon.
Topics & Concepts
AnsatzHamiltonian (control theory)Spectral lineValence (chemistry)Coupled clusterPhysicsX-ray photoelectron spectroscopyAtomic physicsK-edgeChemistrySuperposition principleAbsorption spectroscopyX-ray absorption spectroscopyMoleculeQuantum mechanicsNuclear magnetic resonanceMathematicsMathematical optimizationAdvanced Chemical Physics StudiesX-ray Spectroscopy and Fluorescence AnalysisInorganic Fluorides and Related Compounds