| Popis: |
A formalism for calculating the shift of surface phonon dispersion curves due to the presence of defects in surface alloys is presented, using the matching technique and an effective field approach that goes beyond the virtual crystal approximation. Numerical results are examplified in the form of surface phonon dispersion curves for random distributions of defects, shifted as a function of defect concentrations, (0⩽c∗⩽1), defect mass (light and heavy), and realistic model values for defect-crystal and defect-defect interactions. Significant shifts ∽30% are found, that would be measurable within instrumental resolution of He atom scattering and EELS. |
