Pressure-induced electronic and structural phase transformation properties in half-metallic PmN: A first-principles approach

The electronic, structural and magnetic properties of half-metallic promethium nitride (PmN) have been studied using first-principles tight-binding linear muffin-tin orbital (TB-LMTO) method within the local-density approximation (LDA). We calculate the total energy, lattice parameter, bulk modulus, magnetic moment, density of states and energy band structures of half-metallic PmN at ambient as well as at high pressure. Both spin-polarised and non-spin-polarised electronic calculations are performed to check the magnetic stability of PmN. It is found that PmN is ferromagnetically stable. From the total energy calculations it is also found that PmN is stable in the NaCl-type structure under ambient conditions. The structural stability of PmN changes under the application of pressure. We predict a structural phase transformation from NaCl- to CsCl-type structure at the pressure of 3.4 GPa. The high-pressure phase of PmN remains half-metallic and ferromagnetic. The calculated equilibrium lattice parameter and bulk modulus are in good agreement with the experimental and theoretical work.