VIBRATION SPECTRA OF DISORDERED CRYSTALLINE SURFACE CLUSTER

A method is presented for the determination of the energies of the localized vibration modes around isolated inhomogeneity, inside a square crystalline surface. The defect breaks the translational symmetry in two directions and gives rise to localized phonons on its neighborhood. Typical dispersion curves for modes of energies along the inhomogeneity are given with their polarizations. These localized modes energies are compared with the vibration modes of the free molecule. The vibration Green's functions are determined for the system and the spectral and state densities are presented numerically for atomic sites that constitute a minimum representation set in the neighborhood of the defect. A hyperfine resonance structure that permits the analysis of the evolution of the dynamics from half-space to others is obtained. This analytic approach is applicable to different surface cluster configurations for the same underlying substrate square symmetry in the present model, which underlies the general character of the method.