ABINITIO UHF CRYSTAL-ORBITAL STUDIES ON FERROMAGNETIC POLYMERS

The ab initio UHF crystal-orbital (UHF-CO) method is used in calculating the electronic band structures of three 1-D radical-type polymers. The total energies per unit cell of four possible states, namely, metallic (M), charge density wave (CDW), spin density wave (SDW) and ferromagnetic (FM) states, have been obtained for these polymers. It was found that their ferromagnetic states have the lowest energies; therefore we conclude that these polymers have ferromagnetic ground states. The conclusion is further supported by CI calculations of polyradical clusters related to these polymers. Moreover, it is also in agreement with the predictions from Ovchinnikov's simple rule for alternate systems. © 1990.