Electron interaction and energy gap of CDW in MX complex

Using the projection method to deal with the electron correlation, it is shown in this paper that the effect of the electron interaction on the energy gap of CDW in the MX chain complex is just contrary to that in the conjugated polymer, although both the CDW gap in MX chain complex and the BOW gap in conjugated polymer are produced by the dimerization. This opposite behaviors originate from the different features of the charge transfer, which takes place from site to site in MX complex, but from bond to bond in conjugated polymer.