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Title: Coupled cluster valence bond theory for open-shell systems with application to very long range strong correlation in a polycarbene dimer

Here, the Coupled Cluster Valence Bond (CCVB) method, previously presented for closed-shell (CS) systems, is extended to open-shell (OS) systems. The theoretical development is based on embedding the basic OS CCVB wavefunction in a fictitious singlet super-system. This approach reveals that the OS CCVB amplitude equations are quite similar to those of CS CCVB, and thus that OS CCVB requires the same level of computational effort as CS CCVB, which is an inexpensive method. We present qualitatively correct CCVB potential energy curves for all low-lying spin states of P 2 and Mn 2 +. CCVB is successfully applied to the low-lying spin states of some model linear polycarbenes, systems that appear to be a hindrance to standard density functionals. We examine an octa-carbene dimer in a side-by-side orientation, which, in the monomer dissociation limit, exhibits maximal strong correlation over the length of the polycarbene.
Authors:
 [1] ;  [1]
  1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 147; Journal Issue: 2; Related Information: © 2017 Author(s).; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1477258
Alternate Identifier(s):
OSTI ID: 1369578

Small, David W., and Head-Gordon, Martin. Coupled cluster valence bond theory for open-shell systems with application to very long range strong correlation in a polycarbene dimer. United States: N. p., Web. doi:10.1063/1.4991797.
Small, David W., & Head-Gordon, Martin. Coupled cluster valence bond theory for open-shell systems with application to very long range strong correlation in a polycarbene dimer. United States. doi:10.1063/1.4991797.
Small, David W., and Head-Gordon, Martin. 2017. "Coupled cluster valence bond theory for open-shell systems with application to very long range strong correlation in a polycarbene dimer". United States. doi:10.1063/1.4991797. https://www.osti.gov/servlets/purl/1477258.
@article{osti_1477258,
title = {Coupled cluster valence bond theory for open-shell systems with application to very long range strong correlation in a polycarbene dimer},
author = {Small, David W. and Head-Gordon, Martin},
abstractNote = {Here, the Coupled Cluster Valence Bond (CCVB) method, previously presented for closed-shell (CS) systems, is extended to open-shell (OS) systems. The theoretical development is based on embedding the basic OS CCVB wavefunction in a fictitious singlet super-system. This approach reveals that the OS CCVB amplitude equations are quite similar to those of CS CCVB, and thus that OS CCVB requires the same level of computational effort as CS CCVB, which is an inexpensive method. We present qualitatively correct CCVB potential energy curves for all low-lying spin states of P2 and Mn2+. CCVB is successfully applied to the low-lying spin states of some model linear polycarbenes, systems that appear to be a hindrance to standard density functionals. We examine an octa-carbene dimer in a side-by-side orientation, which, in the monomer dissociation limit, exhibits maximal strong correlation over the length of the polycarbene.},
doi = {10.1063/1.4991797},
journal = {Journal of Chemical Physics},
number = 2,
volume = 147,
place = {United States},
year = {2017},
month = {7}
}

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