Electronic structures and Li intercalation of AuCN and CuCN crystals and nanowires

Based on PBE-D2 energy calculations in combination with LDA band structure analysis, we have investigated the electronic structures and energetics of MCN crystals and their nanowires, where M = Au or Cu. The CuCN crystal and nanowires are semiconductors that exhibit band gaps much larger than their AuCN counterparts. This is because the former adopts the same structure as AgCN, which is different from the AuCN structure. In addition, our calculations show that Li atoms can be intercalated in these systems with no significant volume change and a stoichiometric ratio of MCNLi, because the Li atoms fit into the space located at the center of three parallel CN groups. Furthermore, the Li intercalation converts the CuCN crystal from the AgCN structure to the AuCN structure.