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Hilbert space multireference coupled cluster tailored by matrix product states.
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SYSNO ASEP 0580139 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Hilbert space multireference coupled cluster tailored by matrix product states. Author(s) Demel, Ondřej (UFCH-W) RID, ORCID, SAI
Brandejs, Jan (UFCH-W) ORCID, RID
Lang, Jakub (UFCH-W) RID, ORCID
Brabec, Jiří (UFCH-W) RID, ORCID
Veis, Libor (UFCH-W) RID, ORCID
Legeza, Ö. (HU)
Pittner, Jiří (UFCH-W) RID, ORCIDArticle number 224115 Source Title Journal of Chemical Physics. - : AIP Publishing - ISSN 0021-9606
Roč. 159, č. 22 (2023)Number of pages 14 s. Language eng - English Country US - United States Keywords HOMO and LUMO ; Hilbert-space multi-reference coupled-cluster method ; Coupled-cluster methods Subject RIV CF - Physical ; Theoretical Chemistry OECD category Physical chemistry R&D Projects GA18-24563S GA ČR - Czech Science Foundation (CSF) GA19-01897S GA ČR - Czech Science Foundation (CSF) Research Infrastructure e-INFRA CZ II - 90254 - CESNET, zájmové sdružení právnických osob
e-INFRA CZ - 90140 - CESNET, zájmové sdružení právnických osobMethod of publishing Open access Institutional support UFCH-W - RVO:61388955 UT WOS 001126141400006 EID SCOPUS 85179772948 DOI 10.1063/5.0174461 Annotation In the past decade, the quantum chemical version of the density matrix renormalization group method has established itself as the method of choice for strongly correlated molecular systems. However, despite its favorable scaling, in practice, it is not suitable for computations of dynamic correlation. Several approaches to include that in post-DMRG methods exist, in our group, we focused on the tailored coupled cluster (TCC) approach. This method works well in many situations. However, in exactly degenerate cases (with two or more determinants of equal weight), it exhibits a bias toward the reference determinant representing the Fermi vacuum. Although sometimes it is possible to use a compensation scheme to avoid this bias for energy differences, it is certainly a drawback. In order to overcome this bias of the TCC method, we have developed a Hilbert-space multireference version of tailored CC, which can treat several determinants on an equal footing. We have implemented and compared the performance of three Hilbert-space multireference coupled cluster (MRCC) variants-the state universal one and the Brillouin-Wigner and Mukherjee's state specific ones. We have assessed these approaches on the cyclobutadiene and tetramethyleneethane molecules, which are both diradicals with exactly degenerate determinants at a certain geometry. We have also investigated the sensitivity of the results on the orbital rotation of the highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) pair, as it is well known that Hilbert-space MRCC methods are not invariant to such transformations. Workplace J. Heyrovsky Institute of Physical Chemistry Contact Michaela Knapová, michaela.knapova@jh-inst.cas.cz, Tel.: 266 053 196 Year of Publishing 2024 Electronic address https://hdl.handle.net/11104/0348905
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