Recent Developments in the Theory of Supralattices

Regular 3D arrays of nanosize clusters can be synthesized in the cages of zeolite frameworks. Such nanocomposites are known as supralattices . The appeal to use zeolites mainly comes from the periodic nature of channels and cages in these structures. Alumino−silicate zeolite frameworks have wide electronic bandgaps and are transparent, which opens up the possibility of forming new guest electronic states within the gap. Revolutionary developments in methods of electronic structure theory make possible the quantitative investigation of such complex systems as supralattices . We discuss recent advances in theoretical methods based on the electronic structure theory and describe several recent applications of these techniques to supralattices. Theory can help answer questions as to what kind of guests are appropriate for a given host and what are the energetics and dynamics of the cluster formation in the zeolite cages. Optical, magnetic, and thermal properties of the resulting composite can now, in some cases, be predicted. As examples, we discuss alkali metals in Si clathrates, sodium−sodalite, zeolite Na-Y, and silicon clusters in silica−sodalite. We emphasize the fundamental aspects of these problems.