Collective modes of SDW in 1D extended Hubbard model at quarter-filling

Abstract We have examined the collective mode of spin density wave (SDW) for a quarter-filled one-dimensional (1D) extended Hubbard model with next-nearest-neighbor repulsive interaction ( V 2 ). Within the random phase approximation (RPA), we obtain a new collective mode associated with 2 k F -charge density wave (CDW), which appears with increasing V 2 ( k F being a Fermi wave number). Furthermore, the corresponding effective Hamiltonian is derived in terms of the velocity of the excitation and the spin susceptibility.