The ABINIT Users Mailing List ( CLOSED )

["Tonatiuh Rangel" <Tonatiuh.Rangel@uclouvain.be>]

Dear Adam,

The coefficients as written in the WFK file are written inside three
loops, as you can check in:
http://www.abinit.org/documentation/helpfiles/for-v5.8/users/abinis_help.html#wavefctfile



       bantot=0                                    <-- counts over all bands
       do isppol=1,nsppol
        do ikpt=1,nkpt
         write(unit) npw,nspinor,nband                    <-- for each k
point
         write(unit) kg(1:3,1:npw)                        <-- plane wave
reduced coordinates
         write(unit) eigen(1+bantot:nband+bantot),        <-- eigenvalues
for this k point
                     occ(1+bantot:nband+bantot)           <-- occupation
numbers for this k point
         do iband=1,nband
          write(unit) (cg(ii+index),ii=1,2*npw*nspinor)   <-- wavefunction
coefficients
         enddo                                            for a single
band and k point
         bantot=bantot+nband
        enddo
       enddo



Internally, the variable cg has the following dimensions:
cg(2,mpw*nspinor*mband*mkmem*nsppol)

THe first index is for the real and complex part.

The second one runs for all bands, k-points and nsppol as in the WFK file:
First it runs over bands, then k-points and at the end on nsppol

Best
Tonatiuh












> Hello Forum,
>
>   I am interested in obtaining the reciprocal lattice expansion
> coefficients
> (often denoted as C_{nk}(\vec G) in TeX) of the periodic part of the Bloch
> functions computed in ABINIT. If I understand correctly the collection of
> these
> coefficients for each band and k-point and reciprocal plane wave is what
> is
> written to the _WFK file. Internally it looks like these coefficients for
> each
> k-point are contained in an array cg(2,1:mcg). But I am having trouble
> understanding the indexing and relating the icg index to the reciprocal
> lattice
> vector and the band number. I have seen that in abinit/doc/theory there
> are
> some pdf files which imply that one should look at the array kg(1:nkg) and
> others, but these arrays don't seem to be used in the current version of
> abinit... but here is where I am stuck. Can anyone tell me how to
> determine the
> correct indexing to relate the C_{nk}(G(icg)) coefficients to the
> appropriate G
> and n and k? Thanks very much in advance for any assistance. Cheers,
>
> Adam
>