  Simulated sliding between an oxidized silicon tip and surface over six
decades of velocity using accelerated molecular dynamics reproduces the
experimentally observed velocity dependence of the friction force. Unlike in
the crystalline case, as increasing force is applied to the amorphous tip
intermediate states arise. These intermediate states serve as critical
transition pathways. The emergence of such states leads to the emergence of a
plateau in sliding velocity at lower sliding speeds and higher temperatures. A
simple theory based on these observations successfully describes both the
experimental and the simulated data.

Materials Science;Statistical Mechanics