Ab Initio Calculations of Effective Exchange Integrals. Possibilities of Superparamagnetic, Mictomagnetic and Amorphous Feromagnetic States for Aggregates of Aromatic Free Radicals and Polymer Radicals

Abstract

Abstract The intermolecular effective exchange integrals (Jab) for clusters of aromatic free radicals were calculated by the ab initio spin-projected unrestricted Hartree-Fock (UHF) Møller-Plesset (APUMP) method. It was found that the sign and magnitude of the calculated Jab-values vary with the stacking modes of the species. Implications of the ab initio results were discussed in relation to possibilities of spin glass, superparamagnetic, micto-magnetic and amorphous ferromagnetic states for aggregates of aromatic free radicals and polymer radicals.