Unitary coupled-cluster based self-consistent polarization propagator theory: a quadratic unitary coupled-cluster singles and doubles scheme

Fuente: arXiv
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Autores principales: Liu, Junzi, Cheng, Lan
Formato: Preprint
Publicado: 2021
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author Liu, Junzi
Cheng, Lan
author_facet Liu, Junzi
Cheng, Lan
contents The development of a quadratic unitary coupled-cluster singles and doubles (qUCCSD) based self-consistent polarization propagator method is reported. We present a simple strategy for truncating the commutator expansion of the UCC transformed Hamiltonian $\bar{H}$. The qUCCSD method for the electronic ground-state includes up to double commutators for the amplitude equations and up to cubic commutators for the energy expression. The qUCCSD excited-state eigenvalue equations include up to double commutators for the singles-singles block of $\bar{H}$, single commutators for the singles-doubles and doubles-singles blocks, and the bare Hamiltonian for the doubles-doubles block. Benchmark qUCCSD calculations of the ground-state properties and excitation energies for representative molecules demonstrate significant improvement of the accuracy and robustness over the previous UCC3 scheme derived using Møller-Plesset perturbation theory.
format Preprint
id arxiv_https___arxiv_org_abs_2107_01099
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Unitary coupled-cluster based self-consistent polarization propagator theory: a quadratic unitary coupled-cluster singles and doubles scheme
Liu, Junzi
Cheng, Lan
Chemical Physics
The development of a quadratic unitary coupled-cluster singles and doubles (qUCCSD) based self-consistent polarization propagator method is reported. We present a simple strategy for truncating the commutator expansion of the UCC transformed Hamiltonian $\bar{H}$. The qUCCSD method for the electronic ground-state includes up to double commutators for the amplitude equations and up to cubic commutators for the energy expression. The qUCCSD excited-state eigenvalue equations include up to double commutators for the singles-singles block of $\bar{H}$, single commutators for the singles-doubles and doubles-singles blocks, and the bare Hamiltonian for the doubles-doubles block. Benchmark qUCCSD calculations of the ground-state properties and excitation energies for representative molecules demonstrate significant improvement of the accuracy and robustness over the previous UCC3 scheme derived using Møller-Plesset perturbation theory.
title Unitary coupled-cluster based self-consistent polarization propagator theory: a quadratic unitary coupled-cluster singles and doubles scheme
topic Chemical Physics
url https://arxiv.org/abs/2107.01099