According to low energy electron diffraction (LEED) measurements, Li atoms form linear incommensurate chains in the missing rows induced by Li adsorption on a Cu(100) surface at room temperature and in the coverage range from 0.375 to 0.4. The motions of these Li atoms in the chains are discussed by the classical molecular dynamics calculation. The vibrational excitation spectra of this system are also calculated. Li atoms are assumed to move not only parallel to the surface but also perpendicular to the surface in the missing row by the periodic potential from the substrate Cu atoms. This situation is treated in an approximate manner to show that the spectra obtained may be observed by spectroscopy measurements such as those made by high resolution electron energy loss spectroscopy.
