  We investigate numerically a simple microscopic model to describe wearless
dry friction between atomically flat contact interfaces without thermal
fluctuations (T=0K). The analysis of the incommensurate ground state shows a
breaking of analyticity when the amplitude $\epsilon$ of the Lennard-Jones
interaction between the both harmonic chains increased beyond a critical value
$\epsilon_c$. By the introduction of a suitable order parameter and using a
finite size scaling we could show that the breaking of analyticity is a second
order phase transition. This transition is often called Aubry transition. By
applying of an uniform external force $F^{ex}$ we have determined the critical
force of static friction $F_c$ above a sliding motion occurs.
