Lattice dynamics of RbI( [formula omitted]) surface studied by high-resolution medium energy ion scattering and molecular dynamics simulation

Abstract

The anisotropy and correlations of the thermal vibrations of the RbI(0 0 1) surface were studied by high-resolution medium energy ion scattering (MEIS) and molecular dynamics (MD) simulation. A new toroidal electrostatic analyzer clearly resolved the two surface peaks from the top and second layer Rb + and I − ions making it possible to extract information about the thermal vibration amplitudes of the top and second layer ions and the correlation between them. In the present MD simulation, each ion is regarded as a point charge accompanied by a dipole moment interacting with other ions via a semiempirical pair potential. We employed the dipole moments calculated by the shell model, giving surface relaxation and rumpling values consistent with our previously obtained result. The surface peaks observed for the [1 1 1] and [0 0 1] incidence were well reproduced by assuming the anisotropy and correlations derived by the MD simulations.