CALCULATION OF ZERO-FIELD SPLITTINGS

Abstract

“Calculations have been made of the theoretically expected values of the zero field splitting parameters D and E for a wide variety of planar aromatic molecules. These splittings have been assumed to originate from electronic spin-spin magnetic dipolar interactions whose expectation values have been evaluated for the lowest triplet state of the molecules, the state observable in electron spin resonance spectroscopy. As in the original work of Gouterman and Moffitt, simple H\”ukcel molecular orbital theory with limited configuration interaction was used and the integrals over Slater atomic orbitals were approximated by the substitution of Gaussian wave functions. Several refinements on the original method were added, including abandonment of the nearest, neighbor approximation and compensation for the excessive rate of falloff of Gaussians relative to Slater functions. These refinements were rendered possible through the use of the. I.B.M. 7090 computer at the M.I.T. computation center.”