Figure 2.

(a) Top view of the AB stacked 3R MoS₂ showing the C_3v symmetry. In the AB stacking, the S atoms in the upper layer are on the top of the Mo atoms in the lower layer (bottom layer is depicted as dimmed). The x- and y- axis corresponds to the zigzag and armchair axis of MoS₂, respectively. The AB stacking changes to the AC stacking under the deformation induced by the positive amplitude of Q_LS along the three equivalent directions r₁, r₂ and r₃. (b) Potential energy surface V(Q_IR, Q_LSx, Q_LSy) on the (Q_LSx, Q_LSy) coordinates for Q_IR = 0 Å$\sqrt{\mu }$ (μ is atomic mass unit). The AB stacking corresponds to the origin (0, 0). Polarization-dependent modulation of the potential energy landscape at (c) Q_IRx = ±5 Å$\sqrt{\mu }$ and (d) Q_IRy = ±5 Å$\sqrt{\mu }$ via anharmonic coupling.