Calculation of the superconducting parameters and pressure effects in non-transition metals

A compact form of the electron-phonon interaction parameter is theoretically derived on the basis of the screened pseudopotential proposed by Veljkovic and Slavic (1972), and applied to a number of non-transition metals. On the basis of this parameter along with the electron-electron repulsive pseudopotential, it is found in agreement with the existing experimental data, that none of the metals Li, Na, K, Mg, Ca and Ba are superconducting. Further it has been observed that for medium and strong coupling superconductors, the computed superconducting transition temperatures are of the order of magnitude of the experimental data. An expression for the volume dependence of T is empirically derived and applied to a number of superconductors by explicitly considering the volume dependence of Fermi momentum. Numerical data for the critical volumes deduced from this formulation are definitely more reliable than the existing results of the other theories. (author)