Moving to even P-richer compositions, all the currently known PSs with P/S = 2 (Ca 4 P 2 S, Sr 4 P 2 S, and Ba 4 P 2 S) have a favorable combination of direct band gaps in the visible and low effective masses. The only compound we could find with P/S = 3 is Zr 2 P 3 S (mp-1215423). This PS is only slightly metastable (18 meV above the convex hull) and is predicted to be a semimetal at the PBE level. Due to the systematic band gap underestimation of the PBE functional, Zr 2 P 3 S might as well be a semiconductor. It is also plausible that other ternary and quaternary compounds with P/S = 3 may exist.