Ab initio Calculation of Magnetic Shielding and Susceptibility. I. Molecular Integrals over Gauge Invariant Gaussian Orbitals.

The analytical solutions· for the integrals needed in the SCF computation of magnetic shielding and susceptibility with gauge invariant Gaurssian atoiniC functions . are \u27described. All the integrals can be expressed in terms of known functions

ESR Parameters of the BF2 Radical

Recently Nelson and Gordy1 measured ESR parameters (g-factor, a) of the BF 2 radical. The authors proposed the geometry of the radical and from the analysis of the hyperfine structure deduced the spin densities on 10B, 11B and F

Ab initio Calculation of Magnetic Shielding and Susceptibility. I. Molecular Integrals over Gauge Invariant Gaussian Orbitals.

The analytical solutions· for the integrals needed in the SCF computation of magnetic shielding and susceptibility with gauge invariant Gaurssian atoiniC functions . are \u27described. All the integrals can be expressed in terms of known functions

Plasma Oscillations in Large Ring Polyenes

The possibility of collective motion of the :n:-electron system has been examined by many authors1- 3• In this context it is interesting to note that much more attention has been devoted to the linear conjugated systems than to the ring ones. Recently Yomosa and Segawa studied collective oscillations (charge density or plasma waves) in ring polyenes using Tomonaga\u27s4 method

Localized Orbitals in Hydrogen-Bonded Systems

The localized orbitals in hydrogen bonded systems are described. The localized orbitals of the systems are composed of the localized orbitals of the proton donors and acceptors. The three- center model for the hydrogen bond is found to be inadequate

HFB-SCF-RPA Treatment of Molecular Excitations

Very recently the Hartree-Fock-Bogoliubov self-consistent-field (HFB: SCF) method was applied to molecular systems1• It was shown that the energy is not an appropriate quantity to show to which extent the pairing interaction is involved and the suggestion was given that perhaps other quantities are more sensitive. In recent time the RPA2 with the Hartree-Fock ground state wave function as the zero order wave function has proved to be very successful in calculating the excitation energies of molecules

Variational Approach to the Correlation Problem in the Molecules

The aim of this work is to apply the variat1onal approach as 1ntroduced by Da Providencia1 to the correlat1on problem. We are interested no·t only in the calculation of the ground state energy, but, even more, in the excitation transition of the treated systems