Intrinsic localized anharmonic modes at surfaces and edges

On the basis of realistic lattice-dynamical models, anharmonic modes have been found at surfaces and edges of crystal lattices. Their associated displacements are not only localized in the direction(s) perpendicular, but also parallel to the surface or the tip of the edge. The stability of such modes is tested by molecular dynamics. In the search for anharmonic edge modes, realistic models for alkali halide crystals have been applied. The investigations of an adlayer system make use of ab initio data for the anharmonicity of the adlayer vibrations.