Avoided crossings in photochemistry

Abstract

Two families of avoided crossings exist: (a) geometry-dependent, and (b) model-dependent. They are consequences of one of three possible molecular orbital patterns (allowed crossing, weakly avoided crossing and near-touching situations). All these cases are illustrated here and their mechanistic implications investigated both in terms of static potential energy surfaces and of dynamic Landau—Zener transition probabilities. © 1975, Walter de Gruyter. All rights reserved.