Valence States of BeO Feynman's Way

Abstract

Energy curves are computed by adding a second-order Feynman diagram to a zero of energy. Third order confirms the goodness of second order. The zero of energy includes charge transfer and polarization. It is an average of a limited configuration-mixing model. Evaluation of diagrams requires one set of model orbitals for all valence states, one set of probability amplitudes for all valence states, and two parameters for each valence state. Parameters are evaluated with the zero of energy. Spectroscopic constants and excitation and dissociation energies approach limits of the chosen basis set. Average (maximum) errors between second order and experiment for X, a, A, and B are 0.9 (2.1) pm for Re; 17 (31) kJ/mol for De; 2 (6) kJ/mol for Te; 35 (45) cm−1 for ωe; and 9 (21) kJ/mol for T∞. Frequencies and bond distances for C do not match any calculated for a single state. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 76: 259–279, 2000