SEMIDIRECT ALGORITHMS IN ELECTRON PROPAGATOR CALCULATIONS

Electron propagator calculations have been executed with a semi-direct algorithm that generates only a subset of transformed electron repuls ion integrals and that takes advantage of Abelian point group symmetry . Diagonal self-energy expressions that are advantageous for large mol ecules are employed. Illustrative calculations with basis sets in exce ss of 200 functions include evaluations of the ionization energies of C-7(2-) and Zn(C5H5)(2). In the former application, a bound dianion ob tains for a D-3h structure. In the latter, many final states of the sa me symmetry are calculated without difficulty. (C) 1994 John Wiley & S ons, Inc.