Theoretical Aspects of Small Molecule Rydberg Photochemistry

Abstract

Since most of the important features of the Rydberg spectroscopy of small molecules have been discussed in detail in the recent literature by Robin (1) and Sandorfy (2) we will concentrate on the theoretical aspects of their photochemical behavior. We have reviewed this subject in some detail (3) so that here we will concentrate on the construction of orbital and singlet state correlation diagrams containing Rydberg components which will permit the reader to rationalize either the photochemical behavior of some simple molecules such as water, ammonia and methane or the results of theoretical calculations on other photofragmentation reactions. The single most important feature of this article will be to show the reader how to add Rydberg orbitale and states to correlation diagrams. It will also permit predicting which reaction surfaces can be correlatively treated at the SCF level, or if configuration interaction (CI) is correlatively required, what will be the major configurational composition of the CI wave function.