Use of rescreened pseudopotentials for the superconductivity of aluminum at finite pressures

Abstract

Use is made of the pseudopotential determined by Dagens, Rasolt, and Taylor to calculate from first principles all the microscopic phonon and electron–phonon properties necessary for the superconducting transition temperature of aluminum, Tc, for zero pressure and for volume changes up to −10%. After fitting the Coulomb pseudopotential parameter μ* at zero pressure, Tc is calculated both by solving the Eliashberg gap equations on the imaginary axis, and by employing the approximate formulae of McMillan and of Leavens. The resulting pressure dependence of Tc is unsatisfactory. One source of error appears to be an insufficient pressure-induced shift of the phonon frequencies, indicating a limitation on the use of these pseudopotentials that is not widely appreciated. However, this is not believed to be the only difficulty and other possibilities are briefly discussed.