Coupled Cluster Green's function formulations based on the effective Hamiltonians

Bauman, Nicholas P.; Peng, Bo; Kowalski, Karol

doi:10.1080/00268976.2020.1725669

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Coupled Cluster Green's function formulations based on the effective Hamiltonians

Bauman, Nicholas P.·Peng, Bo·Kowalski, Karol

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Abstract

In this work, we demonstrate that the effective Hamiltonians obtained with the downfolding procedure based on double unitary coupled cluster (DUCC) ansatz can be used in the context of Green’s function coupled cluster (GFCC) formalism to calculate spectral functions of molecular systems. This combined approach (DUCC-GFCC) provides a significant reduction of numerical effort and good agreement with the corresponding all-orbital GFCC methods in energy windows that are consistent with the choice of active space. These features are demonstrated on the example of two benchmark systems: H 2 O and N 2 , where DUCC-GFCC calculations were performed for active spaces of various sizes.

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74 ATOMIC AND MOLECULAR PHYSICS Green function coupled cluster electronic structure methods quantum computing

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Bauman, Nicholas P., Peng, Bo, Kowalski, Karol. 2020-02-12. Coupled Cluster Green's function formulations based on the effective Hamiltonians. https://doi.org/10.1080/00268976.2020.1725669

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