Quasiparticles in σ-conjugated polymers

Conformations of quasiparticle defects (positive and negative polaron and exciton) of oligosilanes consisting of up to 10 repeating units are determined. The polaron conformations computed by the ROHF, UHF and B3LYP methods are compared. Conformations of the positive and negative polarons of oligo[methyl(phenyl)silane] (six repeating units) are determined by means of the ROHF and B3LYP methods. Conformation of the exciton is determined by means of the ab initio configuration interaction (CIS) method. The results are compared with those for the unsubstituted oligosilane.