path lengths and becomes extremely time consuming for long aperiodic paths. The vertical distance between the two fixed regions of the slab was kept constant during these calculations and at the equilibrium distance of the non-sheared slab, i.e. corresponding roughly to zero load. The results for the $0^\circ$ path are shown in figure \[fig:3\].

![A comparison between our friction model and a shearing simulation for the periodic $0^\circ$ sliding path at zero load. The entire period is shown. The solid (cyan) line and the dashed (magenta) line give the unrelaxed and relaxed energy curves for the quasi-static model, as seen also in figure \[fig:2\]. The black circles are fully relaxed data points of the shearing calculation.[]{data-label="fig:3"}](shear_0.pdf){width="0.9\linewidth"}

In the beginning the energy of the sheared slabs follows the relaxed energy curve from our proposed quasi-static model, but starts to deviate in the vicinity of its first maximum at about $l=\unit[1]{\AA}$. The sheared system is not fully relaxing into the total energy minimum but is still pinned in the potential well of the starting position, a common feature in stick-slip sliding. The slip is initiated only at the end of the period, where the built up stain energy of $E_{\mathrm{shear}}(0^\circ)=\unit[207]{meV}$ is dissipated 