EOM-CC Methods with Approximate Triple Excitations for NEXAFS and XPS

Abstract

A number of iterative and perturbative approximations to the full equation-of-motion coupled cluster method with single, double, and triple excitations (EOM-CCSDT) are evaluated in the context of calculating the K-edge core-excitation and core-ionization energies of several small molecules. Several of these methods are found to accurately reproduce the full EOM-CCSDT energies well, in particular the EOM-CCSD* method which, when using the core-valence separation (CVS) ansatz, scales rigorously with the sixth power of molecular size. The EOM-CCSDR(3) method, which has been used previously to include triples effects in a cost-effective manner was found to perform rather poorly, although the precise cause has not been determined. These results highlight that very accurate NEXAFS and XPS spectra for molecules with first-row atoms can be computed at a cost not much larger than that for EOM-CCSD.

11 pages, 3 figures, supplementary information

References in corpus (5)

• Highly Accurate Prediction of Core Spectra of Molecules at Density Functional Theory Cost: Attaining sub eV Error from a Restricted Open-Shell Kohn-Sham Approach
• eT 1.0: an open source electronic structure program with emphasis on coupled cluster and multilevel methods
• Excited States via Coupled Cluster Theory without Equation-of-Motion Methods: Seeking Higher Roots with Application to Doubly Excited States and Double Core Hole States
• Efficient Simulation of Near-Edge X-ray Absorption Fine Structure (NEXAFS) in Density-Functional Theory: Comparison of Core-Level Constraining Approaches
• An analysis of the performance of coupled cluster methods for core excitations and core ionizations using standard basis sets

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