  We show an efficient way to compute the electron-phonon coupling constant,
$\lambda$, and the superconducting transition temperature, Tc from
first-principles calculations. This approach gives rapid convergence of Tc with
respect to the size of the k-point mesh, and is seamlessly connected to the
formulation used in large molecular systems such as alkali fullerides where
momentum dependence can be neglected. Since the phonon and electron-phonon
calculations are time consuming particularly in complicated systems, the
present approach will strongly reduce the computational cost, which facilitates
high-throughput superconducting material design.
