Electronic structure of silicon-oxygen high polymers

The electronic structure of silicon-oxygen high polymers (siloxane and siloxene) have been calculated by the first-principle local-density-functional method. Oxygen's lone-pair (OLP) states play an important role in the electronic structure of these polymers, in accordance with oxygen's spatial position. In siloxane, where oxygen atoms position in the Si skeleton backbone, non-bonding (n) electrons in the OLP states cut Si's σ-electron delocalization, and widen the band gap. On the contrary, when oxygen atoms are located outside of the Si skeleton (siloxene), the characteristic σ-n mixing occuring at the band-edge states has a potential to reduce the band gap.