We report an ab initio study of Sb2S3, Sb2Se3, and Bi2S3 sesquichalcogenides at hydrostatic pressures up to 60 GPa. explore the possibility that C2/m, C2/c, disordered Im-3m, I4/mmm phases observed in with heavier cations, viz. Bi2Se3, Bi2Te3, Sb2Te3, could also be formed Bi2S3, as suggested from recent experiments. Our calculations show C2/c phase is not energetically favorable any three compo...