A perturbative approach to multireference equation-of-motion coupled cluster
| Autor: | Róbert Izsák, Marcel Nooijen, Frank Neese, Marvin H. Lechner |
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| Rok vydání: | 2021 |
| Předmět: |
Physics
010304 chemical physics Biophysics Equations of motion 010402 general chemistry Condensed Matter Physics 01 natural sciences 0104 chemical sciences Coupled cluster Amplitude Similarity (network science) Excited state 0103 physical sciences Perturbation theory (quantum mechanics) Physics::Chemical Physics Physical and Theoretical Chemistry Molecular Biology Mathematical physics |
| DOI: | 10.6084/m9.figshare.14784359 |
| Popis: | We introduce a variant of the multireference equation-of-motion coupled-cluster (MR-EOMCC) method where the amplitudes used for the similarity transformations are estimated from perturbation theory. Consequently, the new variant retains the many-body formalism, a reliance on at most two-body densities, and the state-universal character. As a non-iterative variant, computational costs are reduced, and no convergence difficulties with near-singular amplitudes can arise. Its performance was evaluated on several test sets covering transition metal atoms, small diatomics, and organic molecules against (near-)full CI quality reference data. We further highlight its efficacy on the weakly avoided crossing of LiF and place MR-EOMCC and the new variant into context with linear response theory. The accuracy of the variant was found to be at least on par with expectations for multireference perturbation theories, judging by the NEVPT2 method. The variant can be especially useful in multistate situations where the high accuracy of the iterative MR-EOMCC method is not required. |
| Databáze: | OpenAIRE |
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