Modeling the Properties of Quartz with Clusters

We illustrate a cluster approach to calculate the electronic properties of αquartz. Cluster approaches to modeling defects and other localized states within crystalline matter have a number of computational advantages when compared to traditional energy band methods. However, the implementation of cluster models has been inhibited by the poor convergence of bulk properties with cluster size. Here we illustrate recent developments in algorithm construction which allow one to consider larger clusters than previously accessible. In particular, we use clusters such as Si18O23H26 and Si25O34H32 to model quartz. We compare these cluster calculations to plane-wave-pseudopotential calculations for crystalline quartz and find very good agreement.