Excited-State Downfolding Using Ground-State Formalisms

Nicholas P. Bauman

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arXiv · 2310.13752

Excited-State Downfolding Using Ground-State Formalisms

Nicholas P. Bauman

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Abstract

Downfolding coupled cluster (CC) techniques are powerful tools for reducing the dimensionality of many-body quantum problems. This work investigates how ground-state downfolding formalisms can target excited states using non-Aufbau reference determinants, paving the way for applications of quantum computing in excited-state chemistry. This study focuses on doubly excited states for which canonical equation-of-motion CC approaches struggle to describe unless one includes higher-than-double excitations. The downfolding technique results in state-specific effective Hamiltonians that, when diagonalized in their respective active spaces, provide ground- and excited-state total energies (and therefore excitation energies) comparable to high-level CC methods. The performance of this procedure is examined with doubly excited states of H$_{2}$, Methylene, Formaldehyde, and Nitroxyl.

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Nicholas P. Bauman. 2023-10-20. Excited-State Downfolding Using Ground-State Formalisms. https://arxiv.org/abs/2310.13752

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