PHONONS IN DISORDERED SYSTEMS. beta -CuZn.

The method of the mean T-matrix is generalized to partially ordered alloys in the presence of diagonal disordered. A determinant equation is obtained for the complex vibrational spectrum of atoms in such systems. The method of a virtual crystal is generalized to include the case of partially ordered alloys with non-diagonal disorder and the frequencies of atomic vibrations on their 'own' and 'alien' sublattices obtained. The vibrational spectrum of beta -CuZn atoms is calculated for different values of the long-range order parameter. The results indicate the presence of hybridization of atomic vibrations on the different sublattices.