Results 241 to 250 of about 49,790 (296)

A method for describing resonance between generalized valence bond wavefunctions

Chemical Physics, 1981
Abstract In a valence bond (VB) description of wavefunctions there may be several distinct but energetically similar bonding structures. Examples include aromatic molecules (e.g. benzene) and excited states of molecules with equivalent chromophores (e.g. glyoxal). The variational generalization of VB theory, the generalized valence bond (GVB) method,
Arthur F. Voter, William A. Goddard
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On the theory of valence and bonding: A further generalization

Journal of Molecular Structure: THEOCHEM, 1986
Abstract Ab initio and semiempirical definitions of atomic valence, anisotropy, and degree of bonding between pairs of atoms have previously been applied to LCAO-MO RHF, UHF or GVB wavefunctions. It is shown that the same definitions can be applied to a CI wavefunction.
Jorge A. Medrano, Hector F. Reale, Roberto C. Bochicchio   +2 more
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Hidden symmetry breaking in a generalized valence-bond solid model

Journal of Physics A: Mathematical and General, 1994
Summary: A `boson' representation for the ground state of the generalized valence-bond solid model is derived. The relation between this expression and the matrix-product representation of Klümper et al is discussed. It is shown that the hidden \(Z_2 \times Z_2\)-symmetry is partially broken in this model.
Totsuka, Keisuke, Suzuki, Masuo
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The generalized valence bond view of molecules; the BH series

Chemical Physics Letters, 1972
Abstract The low-lying states of B, BH, BH 2 , and BH 3 are analyzed in terms of the orbitals obtained from generalized valence bond (GVB) calculations. We find that the geometries, symmetries, and qualitative form of the potential surfaces can be understood in terms of simple ideas involving the atomic orbitals. These same ideas can be used in many
W.A. Goddard, R.J. Blint
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An approximate diatomics in molecules formulation of generalized valence bond theory

Journal of Computational Chemistry, 2007
AbstractThe slow computational speed of the generalized valence bond perfect pairing method (GVB‐PP) has been an impediment to its routine use. We have addressed this problem by employing a diatomics in molecules Hamiltonian derived from a second quantization perturbation approach.
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Pseudospectral generalized valence-bond calculations: Application to methylene, ethylene, and silylene

The Journal of Chemical Physics, 1990
The pseudospectral (PS) method for self-consistent-field calculations is extended for use in generalized valence-bond calculations and is used to calculate singlet–triplet excitation energies in methylene, silylene, and ethylene molecules and bond dissociation and twisting energies in ethylene.
Jean-Marc Langlois, Richard P. Muller, Terry R. Coley, William A. Goddard, Murco N. Ringnalda, Youngdo Won, Richard A. Friesner   +6 more
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A generalized formalism of the quantum theory of valence and bonding

Journal of Computational Chemistry, 1985
AbstractGeneral definitions of valence, degree of bonding between pairs of atoms, and atomic anisotropy and reactivity are given. They can be applied to closed‐ or open‐shell molecular wave functions (in the semiempirical, quasi or full ab initio SCF levels), as well as to GVB ones. The properties and usefulness of the definitions are discussed as well
Mario A. Natiello, Héctor F. Reale, Jorge A. Medrano   +2 more
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Optimization of the Generalized Valence Bond Method for Vector Processors

Journal of Computational Chemistry, 1986
AbstractThe Generalized Valence Bond [GVB(pp)] multiconfiguration self‐consistent field wave function optimization program has undergone substantial revision in migration from serial scalar computers (like IBM and VAX) to the FPS‐164, a minisupercomputer. Many of the code optimization strategies applied to the GVB program are portable and applicable to
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Generalized valence bond description of multiple bonds

Journal of the American Chemical Society, 1988
Peter A. Schultz, Richard P. Messmer
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Perfect pairing valence bond generalization of self-consistent electron pair theory

The Journal of Chemical Physics, 1980
A generalization of the self-consistent electron pairs (SCEP) method for correlated wave functions is presented which makes possible the use of multiconfiguration reference wave functions that have the form of a generalized valence bond, perfect pairing (GVB/PP) wave function.
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