Configuration interaction extension of AGP for incorporating inter-geminal correlations
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arXiv
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| Format: | Preprint |
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2026
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| _version_ | 1866915938979282944 |
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| author | Kawasaki, Airi Gao, Fei Scuseria, Gustavo E. |
| author_facet | Kawasaki, Airi Gao, Fei Scuseria, Gustavo E. |
| contents | In this paper, we develop a class of antisymmetrized geminal power configuration interaction (AGP-CI) wave functions that extend the AGP framework by incorporating inter-geminal correlations through a CI expansion. To make these wavefunctions computationally tractable, we evaluate them by rewriting the AGP-CI ansatz as a linear combination of AGPs (LC-AGP), for which overlaps and Hamiltonian matrix elements can be computed with standard AGP machinery. Motivated by border-rank decompositions, we further reorganize this ansatz into a compact linear combination of AGPs depending on a small deformation parameter $τ$, which controls how closely the truncated expansion approximates the full AGP-CI state. Benchmark applications to the Hubbard model and to the small molecules H$_2$O and N$_2$ demonstrate that the proposed wavefunctions achieve consistently high accuracy and outperform the LC-AGP, particularly for systems with more electrons and in strongly correlated regimes. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_14115 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Configuration interaction extension of AGP for incorporating inter-geminal correlations Kawasaki, Airi Gao, Fei Scuseria, Gustavo E. Chemical Physics Strongly Correlated Electrons In this paper, we develop a class of antisymmetrized geminal power configuration interaction (AGP-CI) wave functions that extend the AGP framework by incorporating inter-geminal correlations through a CI expansion. To make these wavefunctions computationally tractable, we evaluate them by rewriting the AGP-CI ansatz as a linear combination of AGPs (LC-AGP), for which overlaps and Hamiltonian matrix elements can be computed with standard AGP machinery. Motivated by border-rank decompositions, we further reorganize this ansatz into a compact linear combination of AGPs depending on a small deformation parameter $τ$, which controls how closely the truncated expansion approximates the full AGP-CI state. Benchmark applications to the Hubbard model and to the small molecules H$_2$O and N$_2$ demonstrate that the proposed wavefunctions achieve consistently high accuracy and outperform the LC-AGP, particularly for systems with more electrons and in strongly correlated regimes. |
| title | Configuration interaction extension of AGP for incorporating inter-geminal correlations |
| topic | Chemical Physics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2604.14115 |