ABSTRACT
Many materials of technological importance, from super-alloys with high strength at elevated temperatures to catalysts for oxidation of harmful gases, involve solutions of two or more crystalline materials with inherent randomness in occupation of lattice sites with their constituent atoms-site disorder. Thus, site disorder is a kind of disorder that results from nonperiodic occupation of lattice sites in a crystal structure. It is different from amorphous disorder in that it does not destroy the long-range periodicity of the lattice sites, except possibly with small local atomic displacements with respect to lattice sites. Computational modeling of these solids is challenging because periodic boundary conditions cannot be applied in the same straightforward way as in perfect crystals. The models employed can be classied in three broad groups (Figure 11.1).
