Showing papers by "Ernest R. Davidson published in 1972"
204 citations
TL;DR: The traditional Roothaan-Hartree-Fock orbitals are not invariant under changes in the partitioning of the Hamiltonian into one and two body operators as mentioned in this paper.
Abstract: The traditional Roothaan‐Hartree‐Fock orbitals are not invariant under changes in the partitioning of the Hamiltonian into one and two body operators. This arbitrariness may be exploited to derive canonical orbitals adapted to specific application in spectroscopy or in correlation energy calculations.
136 citations
TL;DR: In this article, the results of a 13 basis function calculation for the water molecule were presented to illustrate the theory developed in Paper I. As expected, the internally consistent self-consistent field results are better for describing spectra than the traditional results.
Abstract: Numerical results of a 13 basis function calculation for the water molecule are presented to illustrate the theory developed in Paper I. As expected, the internally consistent self‐consistent‐field results are better for describing spectra than the traditional results. Orbitals specifically adapted to each transition are still better. No choice of orbitals tried here was really satisfactory for a configuration interaction or perturbation calculation of the correlation energy.
38 citations
TL;DR: In this paper, the effect of unitary transformations among the occupied orbitals of the beryllium atom is discussed, and it is shown that pair-pair interaction energies become large for choices other than the canonical Roothaan-Hartree-Fock orbitals.
Abstract: The effect of unitary transformations among the occupied orbitals of the beryllium atom is discussed. It is shown that pair‐pair interaction energies become large for choices other than the canonical Roothaan‐Hartree‐Fock orbitals. The many‐body perturbation theory diagrams responsible for these effects are discussed.
23 citations