MECHANICAL HYSTERESIS ON AN ATOMIC-SCALE

A micromechanical hysteresis associated with intimate atomic force mic roscopy (AFM) on the Si(100) surface is discovered using ab initio tot al energy pseudopotential density functional calculations. It is predi cted that it is possible to cycle repeatedly between two buckled confi gurations of a surface dimer along two different paths, one of which i nvolves a discontinuous change of the equilibrium dimer-angle, by vary ing appropriately the vertical movement of the AFM tip. This microscop ic mechanical hysteresis effect should be detectable experimentally in low temperature AFM measurements.