STUDIES OF THE FERROMAGNETIC STATE IN QUASI-ONE-DIMENSIONAL ORGANIC POLYMER FERROMAGNETS

The possible ferromagnetic ground state of pi-conjugated alternant hyd rocarbon chains with unequal number of atoms on two sublattices is stu died by the peierls-Hubbard model. Allowing for full lattice relaxatio n, a set of self-consistent iterative equations are established to stu dy this system. The stabilities of the possible ferromagnetic ground s tates with respect to two kinds of unsymmetric site energies are also studied. We find that the ground state of the system is a stable ferro magnetic state as a result of the topological structure of the network and the electron-electron interaction. And the unsymmetric site energ ies, induced by substitutions, will severely weaken the stability of t he ferromagnetic ground state.