The ABINIT Users Mailing List ( CLOSED )

[Matthieu Verstraete <mjv500@york.ac.uk>]

Hi,

The gkk file format can be read out from the source code for mrggkk. The 
simplest thing for you is to use anaddb, though. It already does the 
reading in of everything, and can calculate the g_kn k'n'(q). You'll 
probably need to intervene in the calls to 07ddb/normsq_gkq. The full 
matrix elements are present, independently of the FS. It's only in the 
routines called in 07ddb/normsq_gkq that the weights for "closeness" to 
the FS are added. There is also an option for keeping the full band 
dependency and not adding the weights, but I have not tested it at all. 
Note that the quantity I play with in normsq_gkq is a kind of squared 
matrix element:
if

g_kn k'n' idir,iatom = <psi_k+q,n' | H'_q,idir,iatom | psi_k,n >

then the matrices contain

gamma_idir,iatom,idir',iatom' = g_kn k'n' idir,iatom g_kn k'n' idir',iatom'

which still depends on q, k, and n,n'

In normsq_gkq this is
1) either averaged over the FS bands or not
2) multiplied by the phonon displacement vector or not (then turned back 
into a cartesian basis).

The bottom line is the same for everybody: my code is messy but commented. 
Please also check the subroutine structure and so on - try to understand 
what it does before asking me for details...

The ascii file is an incidental output, which should serve at some point 
to compare with pwscf output. Another future project.

I have the impression I've been through this before on the forum. Please 
search it before posting. There are also other people working on band 
dependent stuff in the elphon, so try to avoid multiple implementations: 
contact Xavier with your exact project.

Matthieu

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Dr. Matthieu Verstraete                 mailto:mjv500@york.ac.uk
Dept. of Physics, University of York,     tel: +44 1904 43 22 08
Heslington, YO10 5DD York, United Kingdom fax: +44 1904 43 22 14