The Gaspari-Gyorffy theory for calculating the electron-phonon interaction $\lambda$ is extended to incorporate a correction to the rigid-muffin-tin approximation (RMTA). This correction is achieved by constructing a potential which has the correct asymptotic behavior at large distances and reduces to essentially a uniform potential well inside the muffin-tin sphere. This method is particularly applicable to the simple metals where the usual RMTA underestimates $\lambda$. The results obtained without any adjustable parameter are in better agreement with the experimental data than those obtained by the RMTA.

• Received 12 May 1980

DOI:https://doi.org/10.1103/PhysRevB.24.3115