quantum-espresso/PHonon/examples/tetra_example

This example illustrates how to calculate electron-phonon interaction
coefficients, for a (444) Monkhorst-Pack (MP) grid of q-points, in fcc Al
by using the optimized tetrahedron method.

IMPORTANT NOTICE: the calculation of electron-phonon coefficients is tricky.
Do not attempt it unless you have a clear idea of the technical problems
(e.g. very slow convergence with k-point grid,, divergence at q=>0 for optical
modes). Carefully read the relevant literature first.

The calculation proceeds as follows (for the meaning of the cited input
variables see the appropriate INPUT_* file)

1) make a self-consistent calculation for Al by using the optimized tetrahedron method
   (occupation = "tetrahedra_opt").

2) make the phonon calculation for the shifted grid of q-points.
   ldisp = .true. and lshift_q = .true.

3) make the electron-phonon calculation for the shifted grid of q-points.
   ldisp = .true. and lshift_q = .true. and  electron_phonon = "lambda"

4) Eliashberg function with alpha2f.x .