Trimethylenemethane. Comparison of multiconfiguration self-consistent field and density functional methods for a non-kekulé hydrocarbon

Christopher J. Cramer, Bradley A. Smith

Research output: Contribution to journalArticlepeer-review

102 Scopus citations

Abstract

Relative energies for different multiplets of trimethylenemethane and methylenecyclopropane are calculated at MCSCF, CASPT2N, and DFT levels of theory. Comparison to the experimentally measured heat of formation for the 3A2′ state and to the experimentally measured 3A2′-1A1 gap permits analysis of the relative importance of active space and basis set selection in the multiconfigurational methods. Such comparison also reveals that while DFT accurately treats triplet trimethylenemethane, there is a limitation in present DFT functionals with respect to accurately treating nondynamic correlation effects for closed-shell singlets in a molecule characterized by degenerate frontier molecular orbitals. Implications for calculations on larger systems are discussed.

Original languageEnglish (US)
Pages (from-to)9664-9670
Number of pages7
JournalJournal of physical chemistry
Volume100
Issue number23
DOIs
StatePublished - Jun 6 1996

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