First-principles verification of CuNNi₃ and ZnNNi₃ as phonon mediated superconductors

Very recently, a new Ni-based antiperovskite nitride superconductor CuNNi₃ has been successfully synthesized. We investigate the electronic structures, phonon dispersions, and electron–phonon interactions of CuNNi₃ and the isostructual ZnNNi₃ by first-principles approach. By analyzing the Eliashberg function we obtain the superconducting transition temperature T_c 3.16 K (3.53 K), which is in good agreement with corresponding experimental T_c 3.2 K (3 K) for CuNNi₃ (ZnNNi₃). They can be verified as conventional phonon-mediated superconductors.