A critique of frontier orbital theory

Abstract

The frontier molecular orbital (FMO) theory has been widely adopted in recent years in the belief that it represents the best available qualitative/semiquantitative treatment of chemistry in terms of quantum theory. While the dubious nature of the approximation on which it is based has been recognized, its apparent success has been taken as sufficient justification. While it has also been recognized that it fails in certain cases, these have been regarded as rare consequences of special circumstances. The claim that FMO theory alone can account for the course of pericyclic reactions, if true, would certainly indicate its superiority to earlier theoretical treatments. However, no in-depth criticism of these claims has as yet been published. The purpose here is to provide such an analysis.