Efficient method to calculate the electron-phonon coupling constant and superconducting transition temperature

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.