DMRG Studies on Properties of Undoped and Doped Molecule-Based Ferromagnetic Chain

By using density matrix renormalization group (DMRG) method a model fororganic molecule-based ferromagnetic chain is proposed. It is found that theground states of undoped and doped systems both exhibit ferrimagneticordering. The e-e repulsion plays an important role in the stability of theferromagnetic state either in doped system or undoped system. For theundoped system, each unit cell contains half of the total spins, which isconsistent with Lieb's theorem. It is convinced that when the system isdoped with one electron, a charge density wave is excited, which decreases the amplitude ofspin density wave, therefore acting against the stability of ferromagnetic state.