VTechWorks staff will be away for the Thanksgiving holiday starting November 24 through November 28, and will not be replying to requests during this time. Thank you for your patience.
Approximate Spin Extended Hartree-Fock theory
Lengsfield, Byron H.
MetadataShow full item record
An approximate spin-extended method is developed in which the Occupation Numbers of the Natural Orbitals of Charge are varied but the orbitals themselves are frozen. A number of techniques for obtaining appropriate Natural Orbitals of Charge are presented and these techniques are employed in semi-empirical and Ab-Initio studies. The molecules chosen for the Ab-Initio study, O₃, F₂ and C₂, are particularly interesting as Restricted Hartree-Fock (RHF) theory fails to provide an adequate description of these systems at their equilibrium geometries. The results of this work indicate that Approximate SpinExtended Hartree-Fock (ASEHF) theory provides a qualitatively acceptable description of bond dissociation, correctly predicts the symmetry of molecular states where RHF theory fails, and provides an efficient means for obtaining a significant amount of correlation energy in molecular calculations. Moreover, when the Generalized Valence Bond form of the ASEHF wavefunction is employed, a particularly useful description of the molecule is obtained. Specifically, the success or failure of the Woodward-Hoffman becomes transparent when the system is analyzed in terms of this wavefunction.
- Doctoral Dissertations