Elastic, electronic, lattice dynamical properties and electron-phonon interaction in the ternary superconductors Sr(GaGe) and Sr(GaSi) at high pressure

We report the results of an ab−initio study of electronic, and detailed lattice dynamical properties of superconducting materials, Sr(GaGe) and Sr(GaSi) under high pressure. The phonon dispersion curves along the high-symmetry directions and phonon frequencies parameters at the Brillouin zone center are computed by using density functional perturbation theory while the elastic constants are calculated in metric-tensor formulation. The Vickers hardness belonging to the compounds is also evaluated clearly. Moreover the band structures, partial densities of states and Fermi surface topologies are discussed in detail. At the same time we advance in-depth understanding of the relationship between the properties determined and superconducting characteristic. The transition temperatures for the compounds have been detected. We find the values of electron-phonon coupling constant as 0.99 and 0.92 for Sr(GaSi) and Sr(GaGe), respectively.