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4.5 Calculation of electron-phonon interaction coefficients with the tetrahedron method

When you perform a calculation of electron-phonon interaction coefficients with the tetrahedron method, you have to use an offset q -point grid in order to avoid a singularity at q = $ \Gamma$ ; you can perform this calculation as follows:

  1. Run pw.x with occupation = "tetraehdra_opt" and K_POINT automatic.
  2. Run ph.x with lshift_q = .true. and electron_phonon = "" (or unset it) to generate the dynamical matrix and the deformation potential (in _ph*/{prefix}_q*/) of each q .
  3. Run ph.x with electron_phonon = "lambda_tetra". You should use a denser k grid by setting nk1, nk2, and nk3. Then lambda*.dat are generated; they contain $ \lambda_{{q \nu}}^{}$ .
  4. Run alpha2f.x with an input file as follows:
    &input
          ne = (a), 
      ltetra = (b), 
      fildyn = (b), 
      mustar = (d), 
      prefix = (e),
    /
    
    1. The number of frequencies for $ \alpha^{2}_{}$F($ \omega$)
    2. = 1 for the linear tetrahedron method, = 2 for the optimized tetrahedron method.
    3. It must be the same as that in ph.x input.
    4. Coulomb pseudo potential $ \mu^{*}_{}$
    5. It must be the same as that in ph.x input.
    Then $ \alpha^{2}_{}$F($ \omega$) , $ \lambda$ , and $ \omega_{{\ln}}^{}$ are calculated.

There is an example in PHonon/example/tetra_example/.


next up previous contents
Next: 5 Parallelism Up: 4 Using PHonon Previous: 4.4 DFPT with the   Contents
2017-03-03