  We employed accurate full potential density-functional theory and linearized
augmented plane wave method to investigate the electronic properties and
possible phase transitions of Cu3N under high pressure. The anti perovskite
structure Cu3N is a semiconductor with a small indirect band gap at ambient
pressure. The band gap becomes narrower with increasing pressure, and the
semi-conducting anti ReO3 structure undergoes a semiconductor to semimetal
transition at pressure around 8.0 GPa. At higher pressure, a subsequent
semimetal to metal transition could take place above 15GPa with a structural
transition from anti ReO3 to Cu3Au structure.
