FragPT2: Multi-Fragment Wavefunction Embedding with Perturbative Interactions
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arXiv
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| Main Authors: | , , , |
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| Format: | Preprint |
| Published: |
2024
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| _version_ | 1866913648803315712 |
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| author | Koridon, Emiel Sen, Souloke Visscher, Lucas Polla, Stefano |
| author_facet | Koridon, Emiel Sen, Souloke Visscher, Lucas Polla, Stefano |
| contents | Embedding techniques allow the efficient description of correlations within localized fragments of large molecular systems, while accounting for their environment at a lower level of theory. We introduce FragPT2: a novel embedding framework that addresses multiple interacting active fragments. Fragments are assigned separate active spaces, constructed by localizing canonical molecular orbitals. Each fragment is then solved with a multi-reference method, self-consistently embedded in the mean field from other fragments. Finally, inter-fragment correlations are reintroduced through multi-reference perturbation theory. Our framework provides an exhaustive classification of inter-fragment interaction terms, offering a tool to analyze the relative importance of various processes such as dispersion, charge transfer, and spin exchange. We benchmark FragPT2 on challenging test systems, including \ce{N_2} dimers, multiple aromatic dimers, and butadiene. We demonstrate that our method can be succesful even for fragments defined by cutting through a covalent bond. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2408_05250 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | FragPT2: Multi-Fragment Wavefunction Embedding with Perturbative Interactions Koridon, Emiel Sen, Souloke Visscher, Lucas Polla, Stefano Chemical Physics Quantum Physics Embedding techniques allow the efficient description of correlations within localized fragments of large molecular systems, while accounting for their environment at a lower level of theory. We introduce FragPT2: a novel embedding framework that addresses multiple interacting active fragments. Fragments are assigned separate active spaces, constructed by localizing canonical molecular orbitals. Each fragment is then solved with a multi-reference method, self-consistently embedded in the mean field from other fragments. Finally, inter-fragment correlations are reintroduced through multi-reference perturbation theory. Our framework provides an exhaustive classification of inter-fragment interaction terms, offering a tool to analyze the relative importance of various processes such as dispersion, charge transfer, and spin exchange. We benchmark FragPT2 on challenging test systems, including \ce{N_2} dimers, multiple aromatic dimers, and butadiene. We demonstrate that our method can be succesful even for fragments defined by cutting through a covalent bond. |
| title | FragPT2: Multi-Fragment Wavefunction Embedding with Perturbative Interactions |
| topic | Chemical Physics Quantum Physics |
| url | https://arxiv.org/abs/2408.05250 |