An empirical interatomic potential approach to structural stability of ZnS and ZnSe nanowires

Structural trends in ZnS and ZnSe nanowires are systematically investigated on the basis of our empirical potential, which incorporates electrostatic energy due to valence-bond and ionic charges. The calculated nanowire cohesive energies for zinc blende, 6H, 4H, and wurtzite structures demonstrate that the stability of crystal structure depends on nanowire diameter. Monte-Carlo calculations to determine the nanowire stacking sequence during nanowire growth also show that nanowires often contain rotational twins, the averaged periodicity of which is almost proportional to nanowire diameter. The periodicity of rotational twins in the nucleation model in which the nucleus consists of facet atoms at the top layer of a nanowire agrees with the observation of rotational twins. The results suggest that our approach is feasible to clarifying structural trends in Zn-based semiconductors nanowires.