Semiempirical self-consistent field-molecular orbitals calculations, employing complete valence orbital basis sets, for methyl-substituted borazines and benzenes

1968 ◽  
Vol 90 (7) ◽  
pp. 1683-1688 ◽  
Author(s):  
Paul M. Kuznesof ◽  
Duward F. Shriver
Keyword(s):  
Molecular Orbitals ◽  
Basis Sets ◽  
Valence Orbital ◽  
Orbital Basis ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field

Universal Gaussian basis functions in relativistic quantum chemistry: atomic Dirac–Fock–Coulomb and Dirac–Fock–Breit calculations

1992 ◽  
Vol 70 (6) ◽  
pp. 1822-1826 ◽  
Author(s):  
G. L. Malli ◽  
A. B. F. Da Silva ◽  
Yasuyuki Ishikawa
Keyword(s):  
Relativistic Quantum ◽  
Basis Set ◽  
Basis Sets ◽  
Interaction Energies ◽  
Gaussian Basis Sets ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Gaussian Basis Set ◽  
Good Agreement

Matrix Dirac–Fock–Coulomb and Dirac–Fock–Breit self-consistent field calculations are performed for a number of neutral atoms. He (Z = 2) through Xe (Z = 54), using the universal Gaussian basis set (18s, 12p, 11d) reported recently by Da Silva etal. The total Dirac–Fock–Coulomb, the Dirac–Fock–Breit, and the Breit interaction energies calculated with this universal Gaussian basis set are in good agreement with the corresponding values obtained by using an extensive well-tempered Gaussian basis set for the He through Ca (Z = 20) atoms. Although this universal Gaussian basis set is inadequate for the calculation of total Dirac–Fock–Coulomb and Dirac–Fock–Breit energies for the Kr, Sr, and Xe atoms, the Breit interaction energies calculated with this basis for these three atoms are in very good agreement with the corresponding Breit interaction energies obtained by using the extensive well-tempered Gaussian basis sets. Work is in progress to generate a more extensive and energetically better universal Gaussian basis set for He through Xe for its use in non-relativistic Hartree–Fock as well as Dirac–Fock self-consistent field calculations on polyatomics involving heavy atoms.

On the dissociation energy of Ti(OH2)+. An MCSCF, CCSD(T), and DFT study

1996 ◽  
Vol 74 (10) ◽  
pp. 1824-1829 ◽  
Author(s):  
A. Irigoras ◽  
J.M. Ugalde ◽  
X. Lopez ◽  
C. Sarasola
Keyword(s):  
Dissociation Energy ◽  
Density Functional ◽  
Basis Sets ◽  
Coupled Cluster ◽  
Functional Theory ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Self Consistent Field Theory ◽  
Effective Core Potentials

The dissociation energy of the Ti(OH2)+ ion–molecule complex was calculated by the multiconfigurational self-consistent field theory, coupled cluster theory, and two density functional theory based methods, using both all-electron basis sets and effective core potentials. The calculations show that approximate density functional theory gives results in better agreement with experiment than either the multiconfigurational self-consistent field theory or the coupled cluster theory, with both all-electron basis sets and effective core potentials. Nevertheless, the optimized geometries and harmonic vibration frequencies are very similar, irrespective of the level of theory used. The interconfigurational energy ordering of the two valence electronic configurations dn−1s and dn−2s2 of the 4F electronic state of the titanium cation were also calculated and are discussed. Key words: ab initio, dissociation energy, ion–molecule complex, effective core potentials, transition metals.

The bond orders of alternant hydrocarbon molecules

1955 ◽  
Vol 229 (1177) ◽  
pp. 251-259 ◽  
Keyword(s):  
Molecular Orbitals ◽  
Bond Orders ◽  
Hydrocarbon Molecule ◽  
Simple Interpretation ◽  
Consistent Field ◽  
Alternant Hydrocarbon ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Hydrocarbon Molecules

The equations which determine the molecular orbitals of an alternant hydrocarbon molecule are discussed. It is proved that the bond orders can be calculated algebraically by various methods without solving the eigenvalue equations. In particular, it is possible to express the bond orders as the sum of a converging series of matrices each of whose terms has a simple interpretation. The naphthalene and benzpyrene molecules are used as illustrations of the various methods. These methods are particularly useful when applied to self-consistent field treatments of these molecules.

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