Theoretical Studies of Two-Photon Absorption Processes. II. Model Calculations

Abstract

Two-photon absorption cross sections are calculated for the hydrogen atom and the hydrogen molecule. Three methods of calculation are employed: (1) a second-order time-dependent perturbation expansion; (2) a ``mean-energy'' approximation; (3) a sum-rule equivalent of perturbation theory. The various methods are compared and evaluated in terms of their general utility in describing double-photon absorption processes.