We present two new exchange-correlation functionals for hybrid Kohn-Sham electronic structure calculations based on the nonseparable functional form introduced recently in the N12 and MN12-L functionals but now with the addition of screened Hartree-Fock exchange. The first functional depends on the density and the density gradient and is called N12-SX; the second functional depends on the densi...

We have employed the Douglas-Kroll-Hess approximation to derive the perturbative Hamiltonians involved in the calculation of NMR spin-spin couplings in molecules containing heavy elements. We have applied this two-component quasirelativistic approach using finite perturbation theory in combination with a generalized Kohn-Sham code that includes the spin-orbit interaction self-consistently and w...

The quantum Monte Carlo (QMC), CASINO code was run to calculate the ground state energy for the hydrogen molecule. The variational Monte Carlo (VMC) technique was used, employing the unrestricted Hartree-Fock (UHF) method, instead of the restricted Hartree-Fock (RHF) method. By altering the VMC steps in the input parameters of the CASINO code, the best ground state energy for the hydrogen molec...

Spin unrestricted calculations using density functional theory can yield wave functions with spin contamination. In conventional post Hartree–Fock calculations ~such as Mo”ller–Plesset perturbation theory!, spin projection can ameliorate some of the problems caused by spin contamination. However, spin projection can seriously degrade the quality of potential energy surfaces calculated by densit...

We perform continuous-choice Brueckner-Hartree-Fock calculations of hypernuclear matter, using the recent Nijmegen potentials for hyperon-nucleon and hyperon-hyperon interactions. Single-particle observables of the various hyperons in bulk matter, as well as properties of singleand double-lambda hypernuclei, employing an extended Skyrme-Hartree-Fock scheme, are presented. We find that the poten...

Molecular magnetizabilities have been calculated at the Hartree-Fock level for a series of diamagnetic molecules: H20, NH3 , CH4 , PH3 , H2S, CO2 , CSO, CS2 , and C3H4 • Gauge invariance is imposed by the use of London atomic orbitals. The results are compared to those obtained with the IGLO (individual gauge for localized orbitals) method and are found to converge faster to the basis set limit...

An efficient and accurate analytic gradient method is presented for Hartree-Fock and density functional calculations using multiresolution analysis in multiwavelet bases. The derivative is efficiently computed as an inner product between compressed forms of the density and the differentiated nuclear potential through the Hellmann-Feynman theorem. A smoothed nuclear potential is directly differe...

A linear response framework is set up for the evaluation of collective excitations in a confined vapour of interacting Bose atoms at finite temperature. Focusing on the currently relevant case of contact interactions between the atoms, the theory is developed within a random phase approximation with exchange. This approach is naturally introduced in a two-fluid description by expressing the den...

a revised analysis of the effect of long-range nonspherical terms in the intermolecular potential on the second virial coefficient is presented with a preferred hartree-fock-dispersion functional (hfd-c) spherical core treatment of the integrations for small intermolecular distances. a set of modified numerical tables for the accurate calculation of the nonspherical contribution to the second v...