Electronic Structure of LiH According to a Generalization of the Valence-Bond Method

The wavefunction of LiH has been calculated according to a generalization of the valence-bond method, called the G1 method, which leads to significantly better energies than the Hartree–Fock method, yet retains an independent-particle interpretation. The total energy of the LiH G1 wavefunction is – 8.017 a.u., which accounts for 36% of the difference between the Hartree–Fock and experimental energies. The G1 molecular orbitals, which are discussed in detail, correspond closely to chemists' intuitive concepts of electron orbitals and display bonding properties more clearly than do the Hartree–Fock orbitals. In particular, the bonding orbitals are nodeless between the nuclei and, when compared to the corresponding atomic orbitals, show increased amplitude over essentially the entire internuclear region. Finally, several one-electron properties calculated from the G1 wavefunction are presented

On Determining Orbital Hybridization

A simple method is presented for calculating the hybridization of any orbital. The dependence of the hybridization upon radial distance from er nucleus is discussed, and a procedure for determining the avemge hybridization is suggested with special con-· sideration for doubly occupied orbitals

Factors Governing Nuclear Geometry and Bond-Orbital Directions in Second Row AH2 Molecules

We have obtained valence bond waivefunctions for the neutral, positive ion, and lower excited states of second row AH2 molecules. A number of simple rules emerge which govern the nuclear geometry and bond-orbital directions. These are explained in terms of valence bond orbital characteristics as well as an analysis of energy components

THE INTERNAL ROTATION BARRIER AND ITS DERIVATIVES WITH RESPECT TO VIBRATIONAL COORDINATES IN METHYL SILANE: THEORETICAL AND EXPERIMENTAL RESULTS

$^{1}$Bernard Kirtman, J. Chem. Phys., 41, 3262 (1964).""Author Institution: Department of Chemistry, University of CaliforniaThe barrier to internal rotation and its derivatives (derivatives of the barrier with respect to internal symmetry coordinates) were calculated for $CH_{3}SiH_{3}$ using small basis sets of Slater orbitals with the Hartree-Fock method and also were dettermined from microwave and infrared $spectra.^{1}$. The computed barrier of 1.98 kcal/mole and its $A_{1}$ symmetry derivatives: ---5.57 kcal/\AA mole for the C-Si stretch; ---1.26 kcal/rad. mole for the Si-C-H bend; and ---2.14 kcal/rad. mole for the Si-C-H bend show very good agreement with the experimental values of 1.67 kcal/mole for the barrier and ---5.42 kcal/\AA mole; ---1.16 kcal/rad. mole; and ---1.55 kcal/rad. mole for the three derivatives. The addition of dorbitals on silicon had no significant effect on the calculated results. The barrier derivatives with respect to the C-H and Si-H stretches were assumed to be negligible in the experimental analysis. The change in geometry as the molecule internally rotates and several force constants were also determined both theoretically and experimentally