We describe perturbative methods for improving finite-basis Hartree-Fock calculations toward the complete-basis limit. The best method appears to offer quadratic error reduction and preliminary numerical applications demonstrate that remarkably accurate Hartree-Fock energies can be obtained.

Ground-state deformations, binding energies, and potential energy surfaces have been calculated for eveneven dysprosium isotopes between 160Dy and 180Dy in the framework of density-dependent Hartree-Fock calculations with BCS pairing correlations. Further deformed Hartree-Fock with angular-momentum projection and band-mixing calculations explore the yrast spectra of the nuclides approaching the...

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...

Quantum chemistry is increasingly performed using large cluster computers consisting of multiple interconnected nodes. For a fixed molecular problem, the efficiency of a calculation usually decreases as more nodes are used, due to the cost of communication between the nodes. This paper empirically investigates the parallel scalability of Hartree-Fock calculations. The construction of the Fock m...

Multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations were performed for states of the 3l3l′, 3l4l′ and 3s5l configurations in the Mg-like ions Ca IX – As XXII and Kr XXV. Valence and core-valence electron correlation effects are accounted for through large configuration state function expansions. Calculated excitation energies ...