Localized orbital SCF and CI studies of ground electronic states

Abstract

Localized orbitals for molecules are determined by solving an appropriate set of SCF equations based on the assumption that orbitals are qualitatively localized initially. Degrees of orbital delocalization and comparisons with canonical SCF solutions are reported for H₂O, NH₃, C₂H₄, and H₂CO. Constraints related to prejudging the degree of localization are also investigated. SCF localization arguments are extended to the determination of virtual orbital transformations and configuration interaction calculations of intraorbital and interorbital contributions to the correlation energy are reported. The application of SCF localized orbital techniques to the description of regions of large molecules is discussed with reference to the amide and carboxylate groups of glycylglycine.