Ayati, Amir;
Burton, Hugh GA;
De Baerdemacker, Stijn;
(2025)
Spin-Symmetry Projected Constrained Unrestricted Hartree–Fock.
Journal of Chemical Theory and Computation
, 21
(11)
pp. 5409-5424.
10.1021/acs.jctc.5c00068.
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Abstract
We introduce an electronic structure approach for spin-symmetry breaking and restoration at the mean-field level. The spin-projected constrained-unrestricted Hartree–Fock (SPcUHF) method restores the broken spin symmetry inherent in spin-constrained-UHF determinants by employing a nonorthogonal configuration interaction (NOCI) projection method. This method includes all possible configurations in spin space compatible with a Clebsch–Gordon recoupling scheme in a NOCI calculation. The tunable one-pair-at-a-time characteristics of the symmetry-breaking process in c-UHF allow us to reduce the computational costs of full projection. SPcUHF is tested on 4-, 6-, and 8-electron systems that exhibit dominant static and/or dynamic correlations.
| Type: | Article |
|---|---|
| Title: | Spin-Symmetry Projected Constrained Unrestricted Hartree–Fock |
| DOI: | 10.1021/acs.jctc.5c00068 |
| Publisher version: | https://doi.org/10.1021/acs.jctc.5c00068 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10210049 |
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