Controlled lateral and perpendicular motion of atoms on metal surfaces

We present the theoretical study of the controlled lateral and perpendicular motion of Xe on the Pt(111) surface. The lateral translation of Xe is manipulated by a tungsten tip of a scanning tunneling microscope. Using molecular statics and dynamics the energetics and different modes of atom translation are revealed. In the controlled and reversible transfer of Xe between two flat Pt(111) surfaces, effective charge on Xe, and the dipole moment of the Xe-Pt bond, are calculated as functions of the Xe-surface separation. The contributions of various mechanisms to the transfer rate of Xe are investigated by using the calculated quantum states of Xe under the applied bias voltage. These are tunneling and ballistic transfer, dipole excitation and excitation due to resonant tunneling of electrons, and electron wind force. We found that a single power law for the transfer rate does not exist in the whole range of applied pulse voltage. At high pulse voltage the transfer rate is dominated by the inelastic electron tunneling. At low pulse voltage the rate due to thermally assisted tunneling and ballistic transfer becomes important.