Accurate Thermochemistry with Multireference Methods: A Stress Test for Internally Contracted Multireference Coupled-Cluster Theory

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dc.authoridErtürk, Murat / 0000-0002-7039-1970
dc.contributor.authorWaigum, Alexander
dc.contributor.authorErtürk, Murat
dc.contributor.authorKoehn, Andreas
dc.date.accessioned2025-01-27T20:11:41Z
dc.date.available2025-01-27T20:11:41Z
dc.date.issued2024
dc.departmentÇanakkale Onsekiz Mart Üniversitesi
dc.description.abstractThe internally contracted multireference coupled-cluster method with single, double and perturbative triple excitations, icMRCCSD(T), was tested for its performance in the context of computational high-accuracy thermochemistry. The results were gauged against the standard single-reference coupled-cluster hierarchy with up to 5-fold excitations. The test set comprised of a selection of first-row dinuclear compounds and the three 3d-transition metal compounds MnH, FeH, and CoH. The results revealed two problems with the current formulation of icMRCCSD(T). First, the choice of the Dyall Hamiltonian as the zeroth-order Hamiltonian, which leads to a biased description of the different orbital subspaces and particularly poor results for the atomic correlation energies, and second, the tendency to overestimate the perturbative correction for triply excited clusters, in particular in the presence of open shells and correspondingly low orbital-energy gaps. The two problems could be solved by resorting to the effective Fock operator as zeroth-order Hamiltonian and by adopting a modified amplitude equation that includes terms quadratic in the pair clusters. A similar modification was recently proposed by Masios et al. (Phys. Rev. Lett. 2023, 131, 186401) in the context of applying single-reference coupled-cluster theory to systems with small or vanishing band gaps and we chose the acronym '(cT*) correction' in analogy to that work. In contrast to the work of Masios et al., additional terms including single excitation clusters were omitted, as these again lead to an overestimation of correlation effects in more difficult cases. We also tested another alternative for the zeroth-order Hamiltonian and additional higher-order corrections for the correlation energy. These extensions did not significantly improve the results and were also computationally more demanding. The improved icMRCCSD(cT*)F method yields very accurate results with errors, relative to accurate benchmarks, better than 2 kJ/mol for total energies and atomization energies for the entire set of examples considered in this work.
dc.description.sponsorshipScientific and Technological Research Council of Turkiye, TUBITAK [TUBITAK-BIDEB-2219]; State of Baden-Wurttemberg through the bwHPC initiative; German Research Foundation (DFG) [INST 40/575-1]; Stuttgart Center for Simulation Science (SimTech)
dc.description.sponsorshipThis work has been financially supported by the Scientific and Technological Research Council of Turkiye, TUBITAK, Grant no: TUBITAK-BIDEB-2219 International Postdoctoral Research Fellowship Program (2019-1). We acknowledge support by the state of Baden-Wurttemberg through the bwHPC initiative and the German Research Foundation (DFG) through grant no INST 40/575-1 FUGG (JUSTUS 2 cluster). A.K. also acknowledges the support by the Stuttgart Center for Simulation Science (SimTech).
dc.identifier.doi10.1021/acs.jpca.4c05819
dc.identifier.endpage10070
dc.identifier.issn1089-5639
dc.identifier.issn1520-5215
dc.identifier.issue46
dc.identifier.pmid39535968
dc.identifier.scopus2-s2.0-85209568108
dc.identifier.scopusqualityQ2
dc.identifier.startpage10053
dc.identifier.urihttps://doi.org/10.1021/acs.jpca.4c05819
dc.identifier.urihttps://hdl.handle.net/20.500.12428/20670
dc.identifier.volume128
dc.identifier.wosWOS:001354008400001
dc.identifier.wosqualityN/A
dc.indekslendigikaynakWeb of Science
dc.indekslendigikaynakScopus
dc.indekslendigikaynakPubMed
dc.language.isoen
dc.publisherAmerican Chemical Society
dc.relation.ispartofJournal of Physical Chemistry A
dc.relation.publicationcategoryinfo:eu-repo/semantics/openAccess
dc.rightsinfo:eu-repo/semantics/closedAccess
dc.snmzKA_WoS_20250125
dc.subject2nd-Order Perturbation-Theory
dc.subjectBasis-Set Convergence
dc.subjectFull Ccsdt Model
dc.subjectElectron Correlation
dc.subjectSize Consistency
dc.subjectTransition-Metals
dc.subjectEnergy
dc.subjectImplementation
dc.subjectMoments
dc.subjectHeat
dc.titleAccurate Thermochemistry with Multireference Methods: A Stress Test for Internally Contracted Multireference Coupled-Cluster Theory
dc.typeArticle

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