CALCULATION OF ZERO-FIELD ELECTRON SPIN RESONANCE COEFFICIENTS OF POLYACENES IN THE TRIPLET STATE BY THE SIMPLEST H\"{u}CKEL APPROXIMATION

Abstract

H\”{u}cked molecular $orbitals^{1}$ in their simplest form (without configuration interaction) were used to calculate the zero-field splitting coefficients D and E of electron spin resonance of the lowest triplet level of phenanthrene, benz (a)-anthracene, 1:2 benznaphthacene, and other polyacenes. While the accuracy attained is decidedly lower than in the more elaborate methods of earlier $investigators^{2,3}$, comparison with published experimental $values^{4,5}$ shows that the right order of magnitude has been attained. It is believed that this approximation is adequate for predicting the orientation of the principal axes of the molecule.