A Similarity Transformed Second-order Approximate Coupled Cluster Method for the Excited States: Theory, Implementation, and Benchmark
We present a novel and cost-effective approach of using a second similarity transformation of the Hamiltonian to include the missing higher-order terms in the second-order approximate coupled cluster singles and doubles (CC2) model. The performance of the newly developed ST-CC2 model has been invest...
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Veröffentlicht in: | arXiv.org 2021-07 |
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Hauptverfasser: | , |
Format: | Artikel |
Sprache: | eng |
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Online-Zugang: | Volltext |
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Zusammenfassung: | We present a novel and cost-effective approach of using a second similarity transformation of the Hamiltonian to include the missing higher-order terms in the second-order approximate coupled cluster singles and doubles (CC2) model. The performance of the newly developed ST-CC2 model has been investigated for the calculation of excitation energies of valence, Rydberg, and charge-transfer excited states. The method shows significant improvement in the excitation energies of Rydberg and charge-transfer excited states as compared to the conventional CC2 method while retaining the good performance of the latter for the valence excited state. The method retains the charge-transfer separability of the CT excited states, which is a significant advantage over the traditional CC2 method. An MBPT2 variant of the new method is also proposed. |
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ISSN: | 2331-8422 |
DOI: | 10.48550/arxiv.2106.13630 |