Electronic structures and metallization of HgS under high pressures: First principles calculations and resistivity measurements

The electronic structures of HgS under high pressures are studied by the first principle calculations and the resistivity measurements under pressures. The widths of the band gaps decrease significantly with increasing pressures, which is consistent with the experimental results of the resistivities. HgS with cinnabar structure is a direct band gap semiconductor under pressure lower than 8 GPa. It becomes an indirect band gap semiconductor under the pressures above 8 GPa. When the pressures are higher than 20 GPa, it turns to a semimetal and becomes metallic after the phase transition to rocksalt structure under 26 GPa.