Abstract: Polarons and bipolarons in mixed halide MX compounds were studied in the frame work of the two-band extended Peierls-Hubbard model.Different from the isolated MX chains,it was found that the segments tend to select impurities in mixed halide compounds.Then the charge confinement and the effect of electron-electron interactions were investigated.Finally the properties of impurities in mixed halide compounds with spontaneous charge transfer were also discussed.

Keywords: 
• mixed halide compounds /
• polarons /
• charge confinement