Electronic excitations in stacked oligothiophenes

Electronic spectroscopy of oligothiophenes is studied using the semi-empiri cal ZINDO methodology. Geometry of the neutral, and doubly charged bipolaro nic forms of oligomers from 3T to 8T are optimized. Their coordinates are t hen used to generate various stacked structures up to tetramers. The effect s of the length of the chains, number of layers in stacks, stacking distanc e between chains, deviation from planarity and number and relative position s of bipolaronic forms on the shapes of the electronic excitations are inve stigated.