  The theory of the 2k_F and 4k_F instabilities in quarter-filled band organic
conductors is revisited. The phase angles of the 2k_F bond and charge density
waves are shown to change as electron correlation is turned on, and this
switching of the phase angle is critical for understanding the bond distortion
patterns in the real materials. Intersite Coulomb interactions in the real
materials must be nonzero but less than a critical value. Both intersite and
intrasite charge density waves are destabilized in the quasi-two-dimensional
regime for realistic parameters, thus explaining the weakening of these phases
in the superconducting materials.
