MANY-ELECTRON, MANY-PHOTON THEORY OF NONSTATIONARY STATES

A number of physical processes, such as autoionization, predissociatio n, ac- or dc-field-induced ionization, multiphoton dissociation, or ch emical transformations, can be formulated as problems involving a nons tationary state satisfying a time-independent complex eigenvalue Schro dinger equation (CESE). The CESE gives rise to all the conceptual and practical difficulties associated with the polyelectronic structures o f excited states, as well as novel ones due to the presence of externa l fields and to the physical significance of the continuous spectrum. In a series of articles from this institute, it has been shown how adv anced electronic structure theory and methods suitable for excited sta tes can be integrated in a practical way into selected elements of the rigorous theory of discrete states interacting with the continuous sp ectrum in order to solve the CESE nonperturbatively and efficiently an d compute properties such as positions and widths of inner hole or mul tiply excited states, multiphoton ionization rates, multichannel predi ssociation lifetimes, nonlinear static and frequency-dependent polariz abilities, and tunneling rates. The present article constitutes a revi ew of the basic features of this theory and its computational methods. (C) 1994 John Wiley & Sons, Inc.