The surfaces are identical but are rotated with respect to each other through an arbitrary misfit angle. The misfit gives rise to the formation of domains where every potential valley contains exactly one particle. They are separated by two sets of shift lines, crossing each other in topological defects. During quasistatic sliding, the whole domain pattern moves perpendicular to the driving force. Critical spring constants for the occurrence of instabilities can be derived.
Friction shows strong dependence on both the misfit angle and the pulling direction.
The relevance of the theoretical study for friction experiments on the nanoscale is discussed. If you want to know about VIKO , an academic club, which cares for children.