Richard A. Heaton

Local‐density Hartree–Fock theory of electronic states of molecules with self‐interaction correction

A scheme for incorporating the self‐interaction correction (SIC) to the local density approximation of the Hartree–Fock theory of electronic structure of molecules is presented. This method is applied to the N2 molecule and the resulting orbital energies and total energy are in good agreement with the Hartree–Fock values.

Density‐functional theory with self‐interaction correction: Application to the lithium moleculea)

The self‐interaction corrected version of the local spin density (SIC‐LSD) theory for electronic structure of many‐electron systems has been applied to the ground state (1Σ+g) and three excited states (3Σ+u, 3Σ+g, and 3Πu) of the lithium molecule. Calculations are performed by using both the symmetry‐restricted and symmetry‐unrestricted molecular orbitals. To facilitate computation with high accuracy, a special curve‐fitting technique is presented. With the Kohn–Sham exchange‐only functional, our results are generally in good agreement with those of multiconfiguration self‐consistent‐field (MCSCF) calculations for the three excited states, but our calculated dissociation energy for the ground state is much lower than the MCSCF and experimental values. Inclusion of the correlation term in the density functional is found to bring the ground‐state dissociation energy very close to the experimental value but has little effect on the dissociation energy of the three excited states. Based on an analysis from th...

Self-interaction correction for energy band calculations: Application to LiCl

Abstract We present a method for incorporating the self-interaction correction (SIC) to the local density approximation in energy-band calculations of crystals. A periodic SIC potential is derived using the Wannier representation. The method is applied to a LiCl crystal yielding remarkable improvement in band gap and core levels. Comparison of the computed density of states is made with photoemission work.

A new density functional for fractionally occupied orbital systems with application to ionization and transition energies

The use of fractional occupation of energy levels in the self‐interaction‐corrected local spin density (SIC‐LSD) theory of electronic energy structure is studied with reference to calculation of ionization and excitation energies. With the original form of the SIC‐LSD energy functional for fractional occupation, the one‐electron eigenvalues exhibit nonlinear dependence on the occupation number. A new SIC‐LSD density functional for fractional occupation based on the general behavior of the universal functional is proposed. The one‐electron eigenvalues derived from this new functional vary quite linearly with the occupation number. This makes it possible to obtain ionization and excitation energies by a simple numerical integration over the occupation number. A one‐point integration gives ionization energies that agree on the average with the results on taking the difference in self‐consistent‐field total energy between the atom and the ion to within 0.4% for the atoms He, Li, Be,...,Ar. Improvement can be ...