Ground state, phonon spectrum, and superconducting properties of the cubic inverse perovskite CuNNi3

• The electronic structure of CuNNi3 is studied using ab initio pseudopotential method.
• Phonons are studied using a linear response theory.
• The low-frequency phonon modes couple more strongly with electrons.
• The calculated TC of 3.34 K is in agreement with the experimental value of 3.2 K.

Using a first-principles approach, based on pseudopotentials and the density functional theory, we have investigated the origin of superconductivity in the cubic inverse perovskite CuNNi3. The electronic results reveal that the states around the Fermi level are mainly derived from Ni d orbitals. The average electron phonon coupling constant and the logarithmically averaged frequency are found to be 0.678 and 165.53 K, respectively. The superconducting transition temperature is estimated as 3.34 K, in good agreement with the experimentally reported value of 3.2 K. We thus conclude that this material is a conventional phonon-mediated superconductor.