On the Theory of the π-Electron System in Porphines

Abstract

The failure of certain LCAO molecular orbital calculations of the spectrum of porphine is attributed to the incorrect assumption of complete ``aromaticity.'' A division of the π-electron system into non-interacting parts is supported by the fact that the dynamical properties of the divided system, as calculated by the free-electron model, are in approximate agreement with experiment. A proof of the equivalency of the LCAO method (with overlap neglected) and an approximation to the free-electron method is indicated for certain dynamical systems.