Structural, electronic, vibrational and superconducting properties of LiFeP pnictide superconductor - An Ab-initio approach

Using the generalised gradient approximation (GGA) and an ultrasoft pseudopotential, we report on the structural, electrical, vibrational, and superconducting properties of LiFeP, an iron pnictide superconductor.  The 3s state of P is regulated in the region considerably below the Fermi level, the 3s state of Li is above the Fermi level, and the 3d state of Fe is close to the Fermi level. The underlying bands close to the Fermi level reveal the metallic character of LiFeP.  The positive frequencies of the phonon dispersion curves confirm the material's dynamical stability. A weak electron-phonon coupling (EPC), a measure of decreased electron scattering, indicates poor superconductivity in the material being studied. However, the big difference between the calculated TC results and the experimental data shows that to improve TC, the electron-phonon interaction needs to be 2.5–3.0 times stronger. Moreover, weak electron-phonon coupling is indicated by the effective interaction strength (N₀V) values and show superconducting nature.