(a) The pressure-dependent energy gain of single Mo–S bond including bond stretching, bond angle distortion, and electrostatic interaction energies. (b) The pressure-dependent interlayer interaction energy of an S atom in 2H_c and 2H_a phases. (c) The metallization transition of MoS₂ as a function of layer number. The solid line is the dividing line. The inset is the pressure-dependent bandgaps for monolayer, bilayer, bulk 2H_c- and 2H_a-MoS₂.