Orbital symmetry and orbital interactions in polymeric band structures: Examples of polyethylene and polysilane

Abstract

In this article, we discuss one aspect of the valence band structure of polyethylene, that is, the existence of a minimum at a low-symmetry point of the first Brillouin zone. The orbital interactions which come into play are analyzed. A minimal basis set and a bond orbital model are used to interpret the bonding and antibonding interactions which influence the energy band structure. Our analysis is confirmed by comparing the properties of the isoelectronic valence bands of polyethylene CH2CH2 and polysilane SiH2SiH2.