Richardson-Gaudin states of non-zero seniority. III. The perfect-pairing limit.

Authors

Paul A Johnson

Published in

The Journal of chemical physics. Volume 165. Issue 7. Aug 21, 2026.

Abstract

Strongly correlated electrons can be treated with a configuration interaction of Slater determinants grouped by their number of unpaired electrons with exponential cost. Papers I and II [P. A. Johnson, J. Chem. Phys. 162, 134106 (2025) and P. A. Johnson, J. Chem. Phys. 163, 081101 (2025)] demonstrated that single reference methods built from Richardson-Gaudin states gave results of similar quality at polynomial cost. In this contribution, the states are simplified substantially, yielding the perfect-pairing state as a reference along with its low-lying excitations. The states are much simpler; the computational cost is substantially reduced; and there is no sacrifice in numerical accuracy. Second-order Epstein-Nesbet perturbative corrections for the valence electrons are similar in quality to the complete active space self-consistent field.

PMID:
42607161
Bibliographic data and abstract were imported from PubMed on 18 Aug 2026.

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