High-level coupled-cluster energetics by Monte Carlo sampling and moment expansions: Further details and comparisons
نویسندگان
چکیده
We recently proposed a novel approach to converging electronic energies equivalent high-level coupled-cluster (CC) computations by combining the deterministic CC(P;Q) formalism with stochastic configuration interaction (CI) and CC Quantum Monte Carlo (QMC) propagations. This article extends our initial study [J. E. Deustua, J. Shen, P. Piecuch, Phys. Rev. Lett. 119, 223003 (2017)], which focused on recovering obtained method singles, doubles, triples (CCSDT) using information extracted from full CI QMC CCSDT-MC, CIQMC approaches truncated at quadruples. It also reports first semi-stochastic calculations aimed that correspond triples, quadruples (CCSDTQ). The ability of recover CCSDT CCSDTQ energies, even when quasi-degeneracies triply quadruply excited clusters become substantial, is illustrated few numerical examples, including F–F bond breaking in F2, automerization cyclobutadiene, double dissociation water molecule.
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ژورنال
عنوان ژورنال: Journal of Chemical Physics
سال: 2021
ISSN: ['1520-9032', '1089-7690', '0021-9606']
DOI: https://doi.org/10.1063/5.0045468