Binary IV-VI compounds in the rock-salt crystal structure can exhibit either bands with normal ordering or inverted bands. The band structures and Fermi surfaces of IV-VI compounds are shown in Figures and. The partial contributions of atomic orbitals to each band suggest that SnTe, SnSe, SnS, GeSe, and GeS in the rock-salt phase have inverted bands at the L-point of the Brillouin zone, while PbTe, PbSe, PbS, and GeTe do not, in agreement with previous studies. All compounds with normal band ordering exhibit a single carrier pocket at the L-point for both the conduction and valence bands, whereas the shapes of the band edges are more diverse for compounds with inverted bands. For example, while SnTe exhibits a single carrier pocket for the conduction and valence bands centered at each L-point (Figure ), each half-pocket breaks into three full carrier pockets that are offset from the L-plane (i.e. the hexagonal zone boundary of the Brillouin zone containing the L-point) in rock-salt SnSe and SnS (Figures ), resulting in an overall 6× increase in the valley degeneracy from N V = 4 to N V = 24. Additionally, rock-salt GeSe and GeS both exhibit a toroidal conduction band Fermi surface (Figures and) as opposed to a single conduction band pocket.