Surface reconstruction and sliding friction:
A Molecular Dynamics study.

Contribution from U. Tartaglino, E. Tosatti (SISSA, Trieste, Italy)

The Au(111) surface reconstructs with a periodicity (l x sqrt(3)), lower l's meaning higher densities. Bending the gold slab give rise to a change of periodicity l, due to strain. The step shown in the inset slides accordingly, letting the top layer change its density. Red line: the concave surface of a bent slab increases its periodicity, the density decrease and the step move forward. Green line: an originally bent slab is suddenly brought back to zero curvature, l decreases (density increases) and the step withdraws. An obscillating lamella with steps should show sliding friction, while a lamella with no steps should not.