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arXiv · 2604.06429

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

Yuhang Ai·Huanchen Zhai·Garnet Kin-Lic Chan
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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.

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Yuhang Ai, Huanchen Zhai, Garnet Kin-Lic Chan. 2026-09-16. Coupled-Cluster Imaginary-Time Evolution and the Coupled-Cluster Energy Variance. https://doi.org/10.1063/5.0339174

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