Phonon Mode Conversion at Planar Interfaces in Crystalline Solids. Harmonic and Anharmonic Interface Potentials

A generalized model of a solid-solid interface is built. The model takes into account additional surface mass densities on both sides of the interface and an anisotropic and/or anharmonic coupling potential. The resonances due to the potential (up to three) manifest themselves by minima (zeros) of transmition and/or extrema in reflected and transmitted waves of different polarization depending on physical properties of the media and of the geometry.