[Untitled]

The broadening of the conduction and valence band edges due to compositional disorder in alloyed materials of finite extent is studied using an sp3s* tight binding model. Two sources of broadening due to configuration and concentration disorder are identified. The concentrational disorder dominates for systems up to at least one million atoms and depends on problem size through an inverse square root law. Significant differences (over 12 meV) in band edge energies are seen depending on choice of granularity of alloy clusters.