Standing State. We additionally define the standing state as any configuration for which one of the nitrogen atoms in the N 2 submerges into the subsurface at the hollow site of the slab. In general, the other nitrogen atom of the molecule interacts with one or more lithium atoms on the surface (Fig. ). This state showed a relatively high variability in N 2 bond length, ranging from 12% to 20%, though the mean bond length change was 14.4%.