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Title: Performance of the spin-flip and multi-reference methods for bond-breaking in hydrocarbons : a benchmark study.

Abstract

Benchmark results for spin-flip (SF) coupled-cluster and multireference (MR) methods for bond-breaking in hydrocarbons are presented. The nonparallelity errors (NPEs), which are defined as an absolute value of the difference between the maximum and minimum values of the errors in the potential energy along bond-breaking curves, are analyzed for (i) the entire range of nuclear distortions from equilibrium to the dissociation limit and (ii) in the intermediate range (2.5-4.5 {angstrom}), which is the most relevant for kinetics modeling. For methane, the spin-flip and MR results are compared against full configuration interaction (FCI). For the entire potential energy curves, the NPEs for the SF model with single and double substitutions (SF-CCSD) are slightly less than 3 kcal/mol. Inclusion of triple excitations reduces the NPEs to 0.32 kcal/mol. The corresponding NPEs for the MR-CI are less than 1 kcal/mol, while those of multireference perturbation theory are slightly larger (1.2 kcal/mol). The NPEs in the intermediate range are smaller for all of the methods. The largest errors of 0.35 kcal/mol are observed, surprisingly, for a spin-flip approach that includes triple excitations, while MR-CI, CASPT2, and SF-CCSD curves are very close to each other and are within 0.1-0.2 kcal/mol of FCI. For a largermore » basis set, the difference between MR-CI and CASPT2 is about 0.2 kcal/mol, while SF-CCSD is within 0.4 kcal/mol of MR-CI. For the C-C bond breaking in ethane, the results of the SF-CCSD are within 1 kcal/mol of MR-CI for the entire curve and within 0.4 kcal/mol in the intermediate region. The corresponding NPEs for CASPT2 are 1.8 and 0.4 kcal/mol, respectively. Including the effect of triples by energy-additivity schemes is found to be insignificant for the intermediate region. For the entire range of nuclear separations, sufficiently large basis sets are required to avoid artifacts at small internuclear separations.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Science Foundation (NSF)
OSTI Identifier:
963627
Report Number(s):
ANL/CHM/JA-59918
Journal ID: ISSN 1089-5639; JPCAFH; TRN: US200918%%41
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Phys. Chem. A; Journal Volume: 111; Journal Issue: 50 ; 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
03 NATURAL GAS; BENCHMARKS; CONFIGURATION INTERACTION; DISSOCIATION; ETHANE; HYDROCARBONS; KINETICS; METHANE; PERFORMANCE; PERTURBATION THEORY; POTENTIAL ENERGY; SIMULATION; SPIN FLIP

Citation Formats

Golubeva, A. A., Nemukhin, A. V., Klippenstein, S. J., Harding, L. B., Krylov, A. I., Chemistry, Univ. of Southern California, and Moscow State Univ.. Performance of the spin-flip and multi-reference methods for bond-breaking in hydrocarbons : a benchmark study.. United States: N. p., 2007. Web. doi:10.1021/jp0764079.
Golubeva, A. A., Nemukhin, A. V., Klippenstein, S. J., Harding, L. B., Krylov, A. I., Chemistry, Univ. of Southern California, & Moscow State Univ.. Performance of the spin-flip and multi-reference methods for bond-breaking in hydrocarbons : a benchmark study.. United States. doi:10.1021/jp0764079.
Golubeva, A. A., Nemukhin, A. V., Klippenstein, S. J., Harding, L. B., Krylov, A. I., Chemistry, Univ. of Southern California, and Moscow State Univ.. Mon . "Performance of the spin-flip and multi-reference methods for bond-breaking in hydrocarbons : a benchmark study.". United States. doi:10.1021/jp0764079.
@article{osti_963627,
title = {Performance of the spin-flip and multi-reference methods for bond-breaking in hydrocarbons : a benchmark study.},
author = {Golubeva, A. A. and Nemukhin, A. V. and Klippenstein, S. J. and Harding, L. B. and Krylov, A. I. and Chemistry and Univ. of Southern California and Moscow State Univ.},
abstractNote = {Benchmark results for spin-flip (SF) coupled-cluster and multireference (MR) methods for bond-breaking in hydrocarbons are presented. The nonparallelity errors (NPEs), which are defined as an absolute value of the difference between the maximum and minimum values of the errors in the potential energy along bond-breaking curves, are analyzed for (i) the entire range of nuclear distortions from equilibrium to the dissociation limit and (ii) in the intermediate range (2.5-4.5 {angstrom}), which is the most relevant for kinetics modeling. For methane, the spin-flip and MR results are compared against full configuration interaction (FCI). For the entire potential energy curves, the NPEs for the SF model with single and double substitutions (SF-CCSD) are slightly less than 3 kcal/mol. Inclusion of triple excitations reduces the NPEs to 0.32 kcal/mol. The corresponding NPEs for the MR-CI are less than 1 kcal/mol, while those of multireference perturbation theory are slightly larger (1.2 kcal/mol). The NPEs in the intermediate range are smaller for all of the methods. The largest errors of 0.35 kcal/mol are observed, surprisingly, for a spin-flip approach that includes triple excitations, while MR-CI, CASPT2, and SF-CCSD curves are very close to each other and are within 0.1-0.2 kcal/mol of FCI. For a larger basis set, the difference between MR-CI and CASPT2 is about 0.2 kcal/mol, while SF-CCSD is within 0.4 kcal/mol of MR-CI. For the C-C bond breaking in ethane, the results of the SF-CCSD are within 1 kcal/mol of MR-CI for the entire curve and within 0.4 kcal/mol in the intermediate region. The corresponding NPEs for CASPT2 are 1.8 and 0.4 kcal/mol, respectively. Including the effect of triples by energy-additivity schemes is found to be insignificant for the intermediate region. For the entire range of nuclear separations, sufficiently large basis sets are required to avoid artifacts at small internuclear separations.},
doi = {10.1021/jp0764079},
journal = {J. Phys. Chem. A},
number = 50 ; 2007,
volume = 111,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}