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

Abstract

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.

References in corpus (5)

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• Crossing conditions in coupled cluster theory
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Cited by in corpus (4)

• Simulating the electronic structure of spin defects on quantum computers
• Quantum simulations of Fermionic Hamiltonians with efficient encoding and ansatz schemes
• A new "gold standard": perturbative triples corrections in unitary coupled cluster theory and prospects for quantum computing
• Equation-of-motion internally contracted multireference unitary coupled-cluster theory