SCF-X αSW calculations on PH3 using a nonempirical scheme for choosing overlapping-sphere radii

Abstract

Detailed results of two SCF‐X αSW calculations on PH₃, one with phosphorus d‐type partial waves (2) and one without (1), are presented and compared with the best Hartree‐Fock calculations. Ionization energies for the 5a₁, 2e, and 4a₁ levels, respectively, are 10.61, 13.42, and 20.55 eV from 1 and 10.37, 13.60, and 20.22 eV from 2, in better agreement with the experimental values of 10.59 and 13.5 eV for the first two levels than any previous first‐principles calculation. Total energies are −342.6114 and −342.6449 hartree from 1 and 2, respectively. Contour maps of the valence‐level wavefunctions and total valence charge density are presented; phosphorus d functions are found to contribute significantly (about 15%) only to the wavefunction for the 2e level, their effect being to promote better P–H overlap. Overlapping atomic sphere radii for the above calculations were chosen by a nonempirical scheme involving satisfaction of the virial theorem and the relative sizes of spheres around each atom which enclose the atomic number of electrons in the initial X αSW molecular charge distribution. Results of several complete PH₃ calculations with varying sphere radii, hydrogen α parameter, and outer sphere position, and their role in developing the scheme for choosing radii, are discussed. Overlapping of the spheres improves the quantitative agreement of the eigenvalues with experiment, but the ordering and semiquantitative spacing of the levels are insensitive to variation in any of the above parameters.