Generalized relativistic small-core pseudopotentials accounting for quantum electrodynamic effects: Construction and pilot applications

Andréi Zaitsevskii*, Nikolai S. Mosyagin, Alexander V. Oleynichenko, Ephraim Eliav

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A simple procedure to incorporate one-loop quantum electrodynamic (QED) corrections into the generalized (Gatchina) nonlocal shape-consistent relativistic pseudopotential model is described. The pseudopotentials for Lu, Tl, and Ra replacing only inner core shells (with principal quantum numbers n ≤ 3 for the two former elements and n ≤ 4 for the latter one) are derived from the solutions of reference atomic SCF problems with the Dirac–Coulomb–Breit Hamiltonian to which the model Lamb shift operator added. QED contributions to atomic valence excitation energies evaluated at the SCF level are demonstrated to exceed the errors introduced by the pseudopotential approximation itself by an order of magnitude. Pilot applications of the new model to calculations of excitation energies of two-valence-electron atomic systems using the intermediate-Hamiltonian relativistic Fock space coupled cluster method reformulated here for incomplete main model spaces are reported. Implications for high-accuracy molecular excited state calculations are discussed.

Original languageEnglish
Article numbere27077
JournalInternational Journal of Quantum Chemistry
Volume123
Issue number8
DOIs
StatePublished - 15 Apr 2023

Funding

FundersFunder number
Data Processing for Mega-science Facilities at National Research Centre
National Research Council Canada
Ministry of Education and Science of the Russian Federation075‐10‐2020‐117
Russian Science Foundation20‐13‐00225

    Keywords

    • excitation energy
    • intermediate Hamiltonians
    • quantum electrodynamics
    • relativistic coupled cluster theory
    • relativistic pseudopotential

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