Wannier function analysis of silicon-carbon alloys

Maximally localized Wannier functions are the basis of a new technique for resolving ambiguous bonding issues for amorphous materials. Geometrical methods using the Wannier function representation provide an insightful chemical picture of local bonding and hybridization in disordered structures. Central to these methods is the notion of treating the Wannier function centres as a virtual atomic species with a well-defined degree of localization. Using Wannier function methods, we classify and quantify the types of bonding present in a sample of the ternary alloy hydrogenated amorphous silicon carbide, C22Si22H20. In addition to the bonding previously observed for this material, we see three-centre bonding and flipping bonds. We identify a cluster defect in our sample associated with these flipping bonds, and observe a temperature dependence of the bond flipping. This effect may be observable using temperature-dependent Raman spectroscopy.