Quasiparticle band structure calculation of monolayer, bilayer, and bulk MoS ₂

Quasiparticle self-consistent GW calculations of the band structures and related effective-mass parameters are carried out for bulk, monolayer, and bilayer MoS ₂. Including excitonic effects within the Mott-Wannier theory, quantitative agreement is obtained between the A, B excitons, measured by absorption, and the calculated exciton gap energies at K. The A-B splitting arises from the valence-band splitting which in the monolayer is entirely due to spin-orbit coupling and leads to spin-split states, while in the bilayer it is a combined effect of interlayer and spin-orbit coupling.