FIRST-PRINCIPLES FINITE-TEMPERATURE SIMULATION OF SURFACE DYNAMICS - SI(111)-(7X7)

Methods to extract information on atom dynamics from a short-duration molecular dynamics simulation based on non-traditional signal-processi ng methods are discussed and illustrated on the dynamics of the (7 x 7 ) reconstructed Si(111) surface. The results of the ab initio simulati on allow an unambiguous assignment of the experimental vibration spect ra and predict several new modes. Correlations are found between dynam ical properties and the local electronic structure of the adatom dangl ing bonds. In addition, evidence is found for pronounced anharmonic ef fects well below room temperature, which can be traced back to soft ad atom bonds.