Scattering of elastic waves by the isolated linear chain of physisorbed atoms on the surface in a two-dimensional waveguide

The scattering and transmission properties of vibrational waves in a perturbed two-dimensional waveguide in the harmonic approximation are presented. The perturbation is characterized by an isolated adatom defect boundary separating two planar waveguide crystalline lattices, illustrated by a linear chain of defect masses. The theoretical approach using the matching procedure for calculating phonon scattering at their domain boundaries is also presented. The reflection and transmission probabilities in the scattering region are calculated and illustrated for heavy and light defect masses. The conductance properties, in full accordance with the Landauer-Buttiker description of electron transport, are also calculated in these two cases. It is shown that the influence of defect masses can be explained by the strong decreases of conductance values caused by the asymmetric Fano resonance type. The realistic example presented here is instructive and may constitute a precursor model for analyzing the scattering of vibrational waves by an isolated defect in the two-dimensional crystalline lattice formed by atoms adsorbed on the surface of crystal substrates such as physisorbed noble gas films on close-packed atomic planes of the metal surface. A detailed discussion on the vibrational waves in the scattering region is given.