Reevaluating electron-phonon coupling strengths: Indium as a test case forab initio and many-body theory methods

Using indium as a test case,we investigate the accuracy of the electron-pho non coupling calculated with state-of-the-art ab initio and many-body theor y methods. The ab initio calculations-where electrons are treated in the lo cal-density approximation, and phonons and the electron-phonon interaction are treated within linear response-predict an electron-phonon spectral func tion alpha(2)F(omega) that translates into a relative tunneling conductance that agrees with experiment to within one part in 10(3). The many-body the ory calculations-where alpha(2)F(omega) is extracted from tunneling data by means of the McMillan-Rowell tunneling inversion method -provide spectral functions that depend strongly on details of the inversion process. For the most important moment of alpha(2)F(omega), the mass-renormalization parame ter lambda, we report 0.9+/-0.1, in contrast to the value 0.805 quoted for nearly three decades in the literature. The ab initio calculations also pro vide the transport electron-phonon spectral function alpha(tr)(2)F(omega) f rom which we calculate the resistivity as a function of temperature in good agreement with experiment. [S0163-1829(98)01245-4].