Spin-Symmetry Projected constrained Unrestricted Hartree-Fock
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arXiv
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| Format: | Preprint |
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2024
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| _version_ | 1866916537818939392 |
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| author | Ayati, Amir Burton, Hugh G. A. De Baerdemacker, Stijn |
| author_facet | Ayati, Amir Burton, Hugh G. A. De Baerdemacker, Stijn |
| contents | We introduce an electronic structure approach for spin symmetry breaking and restoration from 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 non-orthogonal 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_16458 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Spin-Symmetry Projected constrained Unrestricted Hartree-Fock Ayati, Amir Burton, Hugh G. A. De Baerdemacker, Stijn Quantum Physics We introduce an electronic structure approach for spin symmetry breaking and restoration from 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 non-orthogonal 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. |
| title | Spin-Symmetry Projected constrained Unrestricted Hartree-Fock |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2412.16458 |