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arXiv · 2406.00989

Exploring the exact limits of the real-time equation-of-motion coupled cluster cumulant Green's functions

Bo Peng·Himadri Pathak·Ajay Panyala·Fernando D. Vila·John J. Rehr·Karol Kowalski
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Abstract

In this paper, we analyze the properties of the recently proposed real-time equation-of-motion coupled-cluster (RT-EOM-CC) cumulant Green's function approach [J. Chem. Phys. 2020, 152, 174113]. We specifically focus on identifying the limitations of the original time-dependent coupled cluster (TDCC) ansatz and propose an enhanced double TDCC ansatz ensuring the exactness in the expansion limit. Additionally, we introduce a practical cluster-analysis-based approach for characterizing the peaks in the computed spectral function from the RT-EOM-CC cumulant Green's function approach, which is particularly useful for the assignments of satellite peaks when many-body effects dominate the spectra. Our preliminary numerical tests focus on reproducing, approximating, and characterizing the exact impurity Green's function of the three-site and four-site single impurity Anderson models using the RT-EOM-CC cumulant Green's function approach. The numerical tests allow us to have a direct comparison between the RT-EOM-CC cumulant Green's function approach and other Green's function approaches in the numerical exact limit.

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Bo Peng, Himadri Pathak, Ajay Panyala, Fernando D. Vila, John J. Rehr, Karol Kowalski. 2024-06-03. Exploring the exact limits of the real-time equation-of-motion coupled cluster cumulant Green's functions. https://arxiv.org/abs/2406.00989

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