NATURE OF THE MAGNETIC INTERACTION OF WURSTER RADICALS IN THE SOLID-STATE

The nature of the spin exchange interaction within the half-filled ban d in one-dimensional stacks of Wurster's radicals in Wurster's red bro mide has been investigated theoretically. The various contributions to the Heisenberg effective exchange integral: direct, kinetic, and indi rect spin exchange are evaluated quantitatively, It has been shown tha t the direct (Coulomb) exchange which causes the ferromagnetic couplin g is small. The negative value of the effective exchange integral betw een Wannier functions, localized within the elementary units, has been determined by the kinetic and indirect (antiferromagnetic) exchange i nteraction.