A supercell model for phonon density of states in a substitutionally disordered alloy

We have calculated vibrational properties for a model of a substitutionally disordered crystal and have used them to estimate the density of states. A “large” cell (currently 16 or 54 atoms) representing the mixed crystal K29Rb71 was repeated on a simple cubic lattice using periodic boundary conditions. Nearest and next nearest neighbour interactions were included. Preliminary results are reported for mass disorder and for force constant changes based on the recent results of Hafner11. One could model a glass by this method as a periodically reproduced amorphous cell.