Abstract
A spin density wave (SDW) state of organic conductors has been studied by examining the charge fluctuation around the mean-field ground state for a system which is given by one-dimensional quarter-filled band, the repulsive interaction of both on-site (U) and nearest-neighbor site (V), the dimerization energy (td) and the anion potential (W0). We calculate the excitation gap due to the commensurability, which appears in the collective mode associated with the phase of the SDW. It is shown that the charge fluctuation is suppressed or enhanced depending on the interplay of mutual interactions and the 4kF-potentials originating from td and W0 where kF denotes the Fermi wave vector.
