The influence of overlap interactions between the bridging ligands and the metal d orbitals on the super-exchange coupling constant are studied by means of ab-initio restricted Hartree-Fock molecular orbital calculations. The interaction between the magnetic d orbitals and the HOMOs of the carboxylate oxygen atoms are investigated in homologous asymmetrically dibridged dicopper(II) complexes wh...

The theory of spin-restricted Brueckner orbitals for high-spin open-shell coupled-cluster wavefunctions is presented. The orbitals are based on single-excitation amplitudes constructed using the symmetric spin–orbital basis coupled-cluster method of Jayatilaka and Lee. It is shown how this approach may be easily implemented within existing open-shell coupled-cluster programs. The method’s perfo...

The charge renormalization procedure for the calculation of the correlation energy of atoms utilizing the analytically known large-D limit solutions for the exact and Hartree–Fock equations is extended to diatomic molecules. This procedure is based on the variation of the nuclear charge, Z , and internuclear distance, R , of the Hartree–Fock Hamiltonian such that the Hartree–Fock energy will be...

The standard Hartree–Fock approximation of the O(N)−invariant φ model suffers from serious renormalization problems. In addition, when the symmetry is spontaneously broken, another shortcoming appears in relation to the Goldstone bosons: they fail to be massless in the intermediate states. In this work, within the framework of out–of– equilibrium Quantum Field Theory, we propose a class of syst...

in this paper, the hartree-fock method has been formulated to investigate some of the ground state properties of quasi-one-dimensional interacting electron gas in the presence of the magnetic field. the bare coulomb interaction between electrons has been assumed. for this system, we have also computed some of its thermodynamic and magnetic properties such as the energy, pressure, incompressibil...

at the present study, different properties of sarin with the formula [(ch3)2cho]ch3pof was studiedin gas phase. geometrical optimizations of sarin, single point calculation, nmr and electricalparameters were carried out in gas phase with the hartee -fock method coupled to 6-31g* basis setsfor all atoms. the results obtained from a comparison between tables and charts came up fordiscussion and a...

We describe the implementation of analytical Hartree-Fock gradients for periodic systems in the code CRYSTAL, emphasizing the technical aspects of this task. The code is now capable of calculating analytical derivatives with respect to nuclear coordinates for systems periodic in 0, 1, 2 and 3 dimensions (i.e. molecules, polymers, slabs and solids). Both closed-shell restricted and unrestricted ...

We discuss several measures of the quality of a molecular orbital. Each requires only that the orbital be associated with a well-defined Fock operator and is thus applicable to both Hartree–Fock and density functional orbitals. One of the measures, the g diagnostic, ranges from g = 0 (perfect) to g = p/2 (poor) and is conceptually simple. We illustrate its usefulness by applying it to a number ...

The classical region of a Bose gas consists of all single particle modes that have a high average occupation and are well described by a classical field. Highly occupied modes only occur in massive Bose gases at ultra-cold temperatures, in contrast to the photon case where there are highly occupied modes at all temperatures. For the Bose gas the number of these modes is dependent on the tempera...

The 1 N hyperfine multiplets of low-7 rotational transitions of the E and Z isomers of HN = CH — C = N, produced by flash pyrolysis from (CH 3 ) 2N —C = N as precursor, were observed and analysed. The quadrupole coupling constants determined are (c-axis perpendicular to the molecular plane): , Xaa/MHz XJUWz XJUHz E H — N = CH — C = N -4 .160(10) +1.658(31) +2.502(31) E H N = C H C = N +0.764(11...