Magic Clusters of MoS2 by Edge S2 Interdimer Spacing Modulation.

Edge atomic and electronic structures of S-saturated Mo-edge triangular MoS2 nanoclusters are investigated using density functional theory calculations. The edge electrons described by the S2-p xp xπ* (S2-Π x) and Mo-d xy orbitals are found to interplay to pin the S2-Π x Fermi wavenumber at kF = 2/5 as the nanocluster size increases, and correspondingly, the ×5 Peierls edge S2 interdimer spacing modulation is induced. For the particular sizes of N = 5 n - 2 and 5 n, where N is the number of Mo atoms at one edge representing the nanocluster size and n is a positive integer, the effective ×5 interdimer spacing modulation stabilizes the nanoclusters, which are identified here to be the magic S-saturated Mo-edge triangular MoS2 nanoclusters. With the S2-Π x Peierls gap, the MoS2 nanoclusters become far-edge S2-Π x semiconducting and subedge Mo-d xy metallic as N → ∞.