Surface-structure determination of the layered compounds Mo${\mathrm{S}}_2$ and Nb${\mathrm{Se}}_2$ by low-energy electron diffraction

The stacking sequence and interplane and interlayer separation of $2H-\mathrm{M}\mathrm{o}{\mathrm{S}}_2$ and $2H-\mathrm{N}\mathrm{b}{\mathrm{Se}}_2$ are determined by the dynamical low-energy-electron diffraction approach. Although lateral reconstructions corresponding to alteration in the bulk stacking sequence at the surface are physically reasonable, we find that such reconstructions do not in fact occur for these two compounds.