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 repulsion integrals and that takes advantage of Abelian point group symmetry. Diagonal self-energy expressions that are advantageous for large molecules are employed. Illustrative calculations with basis sets in excess of 200 functions include evaluations of the ionization energies of C72− and Zn(C5H5)2. In the former application, a bound dianion obtains for a D3h structure. In the latter, many final states of the same symmetry are calculated without difficulty.