New Alternatives for Accurate Electronic Structure Calculations of Potential Energy Surfaces Involving Bond Breaking

TitleNew Alternatives for Accurate Electronic Structure Calculations of Potential Energy Surfaces Involving Bond Breaking
Publication TypeBook Chapter
Year of Publication2007
AuthorsPiecuch, P, Pimienta, ISO, Fan, P-D, Kowalski, K
Book TitleElectron Correlation Methodology
Series TitleACS Symposium Series
Volume958
PublisherAmerican Chemical Sociegy
CityWashington, DC
ISBN NumberISBN13: 9780841238435
Abstract

The method of moments of coupled-cluster equations (MMCC) is extended to potential energy surfaces involving multiple bond breaking by developing the quasi-variational (QV) and quadratic (Q) variants of the MMCC theory. The QVMMCC and QMMCC methods are related to the extended CC (ECC) theory, in which products involving cluster operators and their deexcitation counterparts mimic the effects of higher-order clusters. The test calculations for N2 show that the QMMCC and ECC methods can provide spectacular improvements in the description of multiple bond breaking by the standard CC approaches.