Genealogical electronic coupling procedure incorporating the Hartree--Fock interacting space and suitable for degenerate point groups. Application to excited states of BH/sub 3/

Journal Article · Tue Jul 01 04:00:00 EDT 1980 · J. Chem. Phys.; (United States)

OSTI ID:5258270

Swope, W C; Schaefer, III, H F; Yarkony, D R

The use of Clebsch--Gordan-type coupling coefficients for finite point groups is applied to the problem of constructing symmetrized N-electron wave functions (configurations) for use by the Hartree--Fock SCF and CI methods of determining electronic wave functions for molecular systems. The configurations are eigenfunctions of electronic spin operators, and transform according to a particular irreducible representation of the relevant group of spatial operations which leave the Born--Oppenheimer Hamiltonian invariant. The method proposed for constructing the configurations involves a genealogical coupling procedure. It is particularly useful for studies of molecules which belong to a group which has multiply degenerate irreducible representations. The advantage of the method is that it results in configurations which are real linear combinations of determinants of real symmetry orbitals. This procedure for constructing configurations also allows for the identification of configurations which have no matrix element of the Hamiltonian with a reference configuration. It is therefore possible to construct a Hartree--Fock interacting space of configurations which can speed the convergence of a CI wave function. The coupling method is applied to a study of the ground and two excited electronic states of BH/sub 3/ in its D/sub 3h/ geometry. The theoretical approach involved Hartree--Fock SCF calculations followed by single and double substitution CI calculations, both of which employed double-zeta plus polarization quality basis sets.

• Research Organization: Department of Chemistry and Materials and Molecular Research Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
• OSTI ID: 5258270
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 73:1; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640305* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Theory-- (-1987)
74 ATOMIC AND MOLECULAR PHYSICS
BORON COMPOUNDS
BORON HYDRIDES
CLEBSCH-GORDAN COEFFICIENTS
ELECTRONIC STRUCTURE
ENERGY LEVELS
EXCITED STATES
FUNCTIONS
GROUP THEORY
HARTREE-FOCK METHOD
HYDRIDES
HYDROGEN COMPOUNDS
MATHEMATICAL MODELS
MATHEMATICS
MOLECULAR MODELS
SELF-CONSISTENT FIELD
WAVE FUNCTIONS