[QE-users] pw_export

[Andrea Ferretti]

Hi Zahra,

> Thank you for your attention.
> I can't download the source of  WanT code, I think there is a  problem about it.

ops, links from the want webpage are still pointing to qe-forge (now 
down). Temporarily, here is a working link

http://userportal.max-centre.eu/sites/default/files/repository/want-2.6.0-beta.tar_.gz



> In addition to pw_export,  I used iotk tool and  I have plane wave coefficients and eigenvalues in xml format. But I have the previous
> problem. How  the G vectors are generated and which of them are chosen and finally the coefficients are written according them?
> 
> If I find the answer of this question, my problem will be solved.  


basically, there are three (with even more variants) formats currently 
working to read QE data,

- pw_export   (obsolete, I'd say)
- qexml       (obsolescent, still supported but probably not for too long)
- qexsd       (ie, the new schema-compliant xml + fortran or hdf5
                binaries; long term support at the moment)

libraries able to read all of them are available (qexpt.f90 and 
qexml.f90, surely in want, also in qe; qexsd.F in yambo and in the next 
release of want)

here is a link with the last (beta!) release of yambo including qexsd
http://userportal.max-centre.eu/sites/default/files/repository/yambo-MaX-R3.tar__1.gz

(have a look in yambo/interfaces/p2y)


concerning the info you need, ie the mapping between the G vectors used to 
represent wfcs at a given kpt and the global G vector set (normally used 
to represent the charge density) is as follows:

- pw_export:

   files stored in $prefix.export/

   mgrid    contains the integer compoenets (reciprocal lattice units) of
            the density G vectors
   grid.x   (x=1,... nk) contains a map (the index array) that, for
            each wcf G points to the corresponding vector in the density
            grid,

            it also contains the actual (integer) components of the g
            vectors (grid array)

   these files are iotk binaries, which can be either read as done in want
   or yambo by qexpt_* routines, or converted to xml and read by other
   means

   as you probably know, to convert these files to xml fmt it is enough to
   type

   iokt convert file.dat file.xml

   the iotk executable is distributed with all the above mentioned codes
   (want, qe, yambo, just look into ./bin/)

- qexml:

   files store in $prefix.save/

   G vectors corresponding to the density stored in gvectors.dat (g array)
   while wfc G-vectors in
   /K00001/gkvectors.dat   (for the first k-point and so on)
   (index array; a 3D grid array is also provided)


- qexsd:

   files stored in $prefix.save/

   density grid is read from file charge-density.dat, wfc grids from files
   wfcXX.dat XX=1,nkpts

   format is either fortran binary or hdf5, you need to use a library
   (such as qexsd.F) to read the data

examples provided at the links above
Andrea


> In  previous posts, you had suggested using the qexml library. I found this library in ~/QE/Modules, but I don't know how can use it.
> 
> Thanks again
> Zahra
> 
> On Fri, Jul 6, 2018 at 4:05 PM, Andrea Ferretti <andrea.ferretti at unimore.it> wrote:
> 
>
>       Dear Zahra,
>
>       the pw_export format is read eg in WanT (www.wannier-transport.org).
>       If you download any recent version, and grep for routine starting with
>
>       qexpt_  in want/src/wannier/*f90
>
>       you'll see how grids are read (in particular see ggrids.f90 and wfc_data.f90)
>
>       Sources of the qexpt library (readin pw_export data) can be found in
>       want/src/baselib/qexpt.f90
>
>       hope it helps
>       Andrea
> 
>
>             I used pw_export to obtain wavefunction. The coefficients of wavefunctions in k-space were written in wfc.* files.
>
>             But I'm confused about grid.* files. In fact I want to find the G vectors ( of grid.* files) that the wavefunction
>             coefficients are written corresponding them.
>
>             I will be very appreciated if any one can explain more about them.
> 
>
>             -------------------------
>             Zahra
>             IPM, Tehran, Iran
> 
> 
> 
> 
> 
> --
> Andrea Ferretti, PhD
> S3 Center, Istituto Nanoscienze, CNR
> via Campi 213/A, 41125, Modena, Italy
> Tel: +39 059 2055322;  Skype: andrea_ferretti
> URL: http://www.nano.cnr.it
> 
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> 
> 
>

-- 
Andrea Ferretti, PhD
S3 Center, Istituto Nanoscienze, CNR
via Campi 213/A, 41125, Modena, Italy
Tel: +39 059 2055322;  Skype: andrea_ferretti
URL: http://www.nano.cnr.it