Coupled-Cluster Imaginary-Time Evolution and the Coupled-Cluster Energy Variance

Abstract:We discuss a coupled-cluster formalism for carrying out imaginary-time evolution from an arbitrary reference, and study the properties of the resulting evolution trajectories. The evolution converges to a solution of the standard coupled-cluster amplitude equations in the long-time limit if a finite valued limit exists, but when such a limit does not exist, the trajectories still contain additional information beyond the standard solutions. We introduce the coupled-cluster energy variance which through its minima identifies physically regularized coupled-cluster amplitudes when the solutions of the amplitude equations are unreasonable. We demonstrate the value of this formalism in several exploratory examples within single- and multi-reference coupled-cluster formulations.

Chemical Physics (physics.chem-ph); Quantum Physics (quant-ph)

arXiv:2604.06429 [physics.chem-ph]

(or arXiv:2604.06429v2 [physics.chem-ph] for this version)

https://doi.org/10.48550/arXiv.2604.06429 Focus to learn more arXiv-issued DOI via DataCite

J. Chem. Phys. 165, 114104 (2026)

https://doi.org/10.1063/5.0339174 Focus to learn more DOI(s) linking to related resources

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