Band structures under (a) and (b) compression strains (ε = −0.5%, −1.0%), and under (c) and (d) tensile strains (ε = 0.5%, 1.0%). The black line indicates the band structure of the strain-free monolayer SnO. The compression strains mainly influence the conduction band around the points X and M; tensile strains mainly influence the conduction band around the X point.