The transferability of molecular fragment canonical orbitals

Dennis L Lichtenberger, Richard F. Fenske

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

The ability of certain canonical orbitals of isolated molecular fragments to transfer largely unchanged to the molecular environment is examined. The separation of fragment canonical orbitals from the total molecular electronic problem is compared with the more familiar separations of atomic core orbitals and fragment localized orbitals. The specific example of the carbonyl functional group in formaldehyde is examined in detail. These studies lead to a new concept of valence electron only calculations in which the molecular valence electrons are assumed to move in an effective field provided by frozen molecular fragment canonical cores. In addition, for the case of assumed fragment canonical orbital transfer, perturbation theory analysis is found to be an efficient method of assessing the quality of the approximate wavefunction, thus eliminating much of the uncertainty as new systems are studied. The methods developed in the course of these studies offer certain practical advantages for the construction of approximate wavefunctions for large molecules. The details of application of these concepts to existing molecular orbtial methods are also presented.

Original languageEnglish (US)
Pages (from-to)4247-4264
Number of pages18
JournalThe Journal of Chemical Physics
Volume64
Issue number11
StatePublished - 1976
Externally publishedYes

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Wave functions
fragments
Orbital transfer
Molecular electronics
orbitals
Electrons
Functional groups
Formaldehyde
Molecules
valence
transfer orbits
molecular electronics
formaldehyde
electrons
perturbation theory
urinary gonadotropin fragment
molecules
Uncertainty

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

The transferability of molecular fragment canonical orbitals. / Lichtenberger, Dennis L; Fenske, Richard F.

In: The Journal of Chemical Physics, Vol. 64, No. 11, 1976, p. 4247-4264.

Research output: Contribution to journalArticle

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