Bootstrap embedding with an unrestricted mean-field bath
Name
214101_1_online.pdf
Description
Published version
Size
1.25 MB
Format
Adobe PDF
Checksum (MD5)
580a459480e18b679b5f2383964f2c7c
Author(s)
Tran, Henry K
Ye, Hong-Zhou
Van Voorhis, Troy
Date Issued
December 1, 2020
Journal
The Journal of Chemical Physics
Publisher
AIP Publishing
Citation
Henry K. Tran, Hong-Zhou Ye, Troy Van Voorhis; Bootstrap embedding with an unrestricted mean-field bath. J. Chem. Phys. 7 December 2020; 153 (21): 214101.
Version
Final published version
Abstract
A suite of quantum embedding methods have recently been developed where the Schmidt decomposition is applied to the full system wavefunction to derive basis states that preserve the entanglement between the fragment and the bath. The quality of these methods can depend heavily on the quality of the initial full system wavefunction. Most of these methods, including bootstrap embedding (BE) [M. Welborn et al; J. Chem. Phys. 145, 074102 (2016)], start from a spin-restricted mean-field wavefunction [call this restricted BE (RBE)]. Given that spin-unrestricted wavefunctions can capture a significant amount of strong correlation at the mean-field level, we suspect that starting from a spin-unrestricted mean-field wavefunction will improve these embedding methods for strongly correlated systems. In this work, BE is generalized to an unrestricted Hartree–Fock bath [call this unrestricted BE (UBE)], and UBE is applied to model hydrogen ring systems. UBE’s improved versatility over RBE is utilized to calculate high spin symmetry states that were previously unattainable with RBE. Ionization potentials, electron affinities, and spin-splittings are computed using UBE with accuracy on par with spin-unrestricted coupled cluster singles and doubles. Even for cases where RBE is viable, UBE converges more reliably. We discuss the limitations or weaknesses of each calculation and how improvements to RBE and density matrix embedding theory these past few years can also improve UBE.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1063/5.0029092
