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arXiv · 2205.10707

Benchmarking the Semi-Stochastic CC(P;Q) Approach for Singlet-Triplet Gaps in Biradicals

Arnab Chakraborty·Stephen H. Yuwono·J. Emiliano Deustua·Jun Shen·Piotr Piecuch
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Abstract

We recently proposed a semi-stochastic approach to converging high-level coupled-cluster (CC) energetics, such as those obtained in the CC calculations with singles, doubles, and triples (CCSDT), in which the deterministic CC($P$;$Q$) framework is merged with the stochastic configuration interaction Quantum Monte Carlo propagations [J. E. Deustua, J. Shen, and P. Piecuch, Phys. Rev. Lett. 119, 223003 (2017)]. In this work, we investigate the ability of the semi-stochastic CC($P$;$Q$) methodology to recover the CCSDT energies of the lowest singlet and triplet states and the corresponding singlet-triplet gaps of biradical systems using methylene, ${\rm (HFH)}^{-}$, cyclobutadiene, cyclopentadienyl cation, and trimethylenemethane as examples.

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Arnab Chakraborty, Stephen H. Yuwono, J. Emiliano Deustua, Jun Shen, Piotr Piecuch. 2022-05-22. Benchmarking the Semi-Stochastic CC(P;Q) Approach for Singlet-Triplet Gaps in Biradicals. https://doi.org/10.1063/5.0100165

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