Investigation of physical properties of LaRu2P2 material by using density functional theory

We have studied the structural, electronic, vibrational and electron-phonon interaction properties of LaRu2P2 adopting in the body-centred tetragonal ThCr2Si2 type of crystal structure with using Density Functional Theory (DFT). The calculated structural parameters are in close agreement with their experimental values. The electronic bands near the Fermi level exhibit a considerable dispersion along the c-axis, indicating that this compound is a three-dimensional metal in spite of the apparent two dimensionality in its atomic structure. From the analysis of the total and partial electronic density of states, we have observed that the states around the Fermi level are contributed by the states originating from Ru atoms, confirming their active role in determining the electronic and superconducting properties of this compound. Using our calculated lattice constant and electronic structure, phonons in LaRu2P2 has been studied by employing a linear response approach based on density functional perturbation theory. This compound is dynamically stable, as no instabilities in the phonon dispersion relations have been found. The most impressive features in the phonon spectrum of this material are the phonon anomalies of the LA branch and the lower-lying TA1 branch along the Γ-G1-Z and Γ-N symmetry directions. We have shown that these phonon anomalies make large contributions to the accumulated electron-phonon coupling parameter. The Eliashberg spectral function has been calculated using the phonon spectrum and the electron-phonon matrix elements. From the integration of the calculated Eliashberg function, the value of accumulated electron-phonon coupling constant λ is found to be 0,85, suggesting that LaRu2P2 is a phonon-mediated superconductor with medium electron-phonon coupling strength. Ru-related vibrations make a large contribution to the electron-coupling parameter due to considerable presence of the Ru d states near the Fermi level. Finally, the value of the electronic specific heat coefficient is calculated to be 10,5 mJ/(molK^2 ), which is in good accordance with the experimentally deduced value of 11,5 mJ/(molK^2 ) . From these results, we have concluded that DFT is succesfully explain the origin of superconductivity in LaRu2P2.