Improved algorithms for renormalized electron propagator calculations

A new algorithm has been developed for renormalized electron propagator met hods that are appropriate for shakeup final states such as the algebraic di agrammatic construction in third order, the two-particle, one-hole Tamm-Dan coff approximation and the nondiagonal, renormalized, second-order approxim ation. All contractions are performed with transformed electron repulsion i ntegrals that are stored on disk. It is formulated for closed-shell ground states and employs spin and point-group symmetry. Contributions from transf ormed integrals with four virtual indices may be computed by a direct algor ithm, where integrals in the atomic basis are recalculated as needed. A rep resentative application to the ionization energies of trans-1,3-butadiene i s discussed. (C) 1999 John Wiley & Sons, Inc.