[Pw_forum] Symmetrized el-ph coupling

[Andrea Marini]

Dear forum users,

  I am trying to use PW to calculate the electron-phonon matrix elements 
(EPME) to perform external  self-energy based calculations.

I have studied the elphon.f90 routine and I have understood the way PH 
builds the EPME and how it sums them in the lambda/gamma factors.

My problem is the call to the symdynph_gq routine to symmetrize the 
el_ph_sum array (that contains the sum of the square EPME).

As I need the EPME and not their square I do not understand how to perform 
the symmetrization on the el_ph_mat array (and not on the summed array 
el_ph_sum) in such a way to get exactly the same results for the physical 
lambda/gamma factors.

Thanks

Andrea Marini
--------------------------------------------------------------------------
                                Andrea MARINI

        Physics Department, University of Rome "Tor Vergata" (Italy)
               - phone: +39-0672594894 - fax: +39-062023507 -

-- andrea.marini at roma2.infn.it - http://www.fisica.uniroma2.it/~marini/ --