Cluster expansion of formation energies and direct enumeration ground-state search results of Cd_1–xZn_xS solid solutions: (a) WZ structure, (b) ZB structure. The “known stru." denotes structures whose energies have been calculated from first-principles. The “known gs” indicates the ground states that have been confirmed by first-principles calculations. The “predicted” denotes structures whose energies have been predicted from the cluster expansion andab initioenergies are known.