Energy gradients and effective density differences in electron propagator theory

Efficient calculations of adiabatic electron binding energies require gradi ents of ground and excited potential energy surfaces. These surfaces may be inferred from reference-state total energies and vertical electron binding energies of the electron propagator. Reference-state total energies from m any-body perturbation theory may be derived from electron propagator theory and gradients of these expressions are already known. The missing informat ion for final-state optimization therefore is provided here. Gradients of e lectron propagator poles (ionization energies and electron affinities) with respect to nuclear positions in the second-order, 2p-h Tamm-Dancoff and no ndiagonal, renormalized, second-order approximations of electron propagator theory are derived. Effective electron density difference matrices corresp onding to these poles are by-products of the derivations. (C) 2000 American Institute of Physics. [S0021-9606(00)30501-3].