Optical Spectrum of MoS${}_2$: Many-body Effects and Diversity of Exciton States

Abstract: We present first-principles calculations of the optical response of monolayer molybdenum disulfide employing the GW-Bethe Salpeter equation (GW-BSE) approach including self-energy, excitonic, and electron-phonon effects. We show that monolayer MoS2 possesses a large and diverse number of strongly bound excitonic states with novel k-space characteristics that were not previously seen experimentally or theoretically. The absorption spectrum is shown to be dominated by excitonic states with binding energy close to $1$~eV and by strong electron-phonon broadening in the visible to ultra-violet range. Our results explain recent experimental measurements and resolve inconsistencies between previous GW-BSE calculations.