Atomic structure and phonons of a Pb ultrathin film on the Al(100) surface

The atomic and phonon structures of a Pb ultrathin film on the Al(100) surface have been theoretically studied. Surface relaxation, local density of vibrational states, and polarization of the phonon modes of adatoms and atoms of a substrate have been discussed. It has been shown that the adsorption of Pb results in the oscillating relaxation of the surface of the substrate and warping of the structure in subsurface layers. Comparative analysis of the vibrational characteristics of the pure surface of the substrate and the surface with adatoms has shown that the adsorptive interaction in the system and its dynamic stability are governed by new vibrational modes that are not inherent in pure Al and Pb surfaces.
This work was supported by the Government of the Russian Federation (Program of Basic Research at State Academies of Sciences for 2013–2020). The numerical calculations were performed at the SKIF Cyberia supercomputer (Tomsk University).