Density matrix renormalization group studies on π-topology and spin alignment of an organic π-conjugated spin system

We carry out density matrix renormalization group (DMRG) calculations to study π-topology and spin alignment of an organic π-conjugated spin system in the Hubbard model. We discuss the spin correlation, the energy gap and the lattice configuration in half-filled and doped systems. It is confirmed that electronic doping can alter the spin state, and the spin alignment is influenced by the parity of the total site number N. The electron-electron interaction is in favour of the ferromagnetic stability of the system. For the hall-filled odd case and the hole-doped even case, there exist strong ferromagnetic correlation and large energy gap in π-conjugated spin systems