  We have studied the optical conductivity of two-dimensional (2D)
semiconducting transition metal dichalcogenides (STMDC) using ab-initio density
functional theory (DFT). We find that this class of materials presents large
optical response due to the phenomenon of band nesting. The tendency towards
band nesting is enhanced by the presence of van Hove singularities in the band
structure of these materials. Given that 2D crystals are atomically thin and
naturally transparent, our results show that it is possible to have strong
photon-electron interactions even in 2D
