Ab initio investigations of the electronic structure and lithium stability in Li2UN2 and LiUN2

摘要

The electronic and magnetic structures of the ternary nitrides Li2UN2 and LiUN2 are examined from ab initio with an assessment of the properties of chemical bonding. Both nitrides are characterized by metallic behavior with a large U 5/density of states leading to finite magnetic moments on the uranium sites, whereas the lithium-free UN2 has insulating character with ～1 eV band gap. The chemical bonding is found mainly between U and N, whereas Li-N shows a small bonding magnitude. The removal of one Li equivalent out of Li2UN2 requires little energy compared to the process of de-intercalating Li from LiUN2 or the departure of a second Li atom from Li2UN2.