The ABINIT Users Mailing List ( CLOSED )

["Adam Sorini" <asorini@gmail.com>]

On Fri, May 23, 2008 at 1:15 AM, Anglade Pierre-Matthieu <anglade@gmail.com> wrote:

Hi,

Rhog is defined as rhog(2,nfftf). Where nfftf is the number of grid
point. rhog(1:i) is the real part of rhog at the ith gread point and
rhog(2,j) the imaginary part of the same number ...

ahha. okay, thanks very much for the information. This does seem to make sense and compare well with my independently performed fourier transform of rhor. I think my confusion comes from the comments in the code. In particular, one reads:

!! rhog(nfft,nspden)= total electron density in electron/bohr**3, reciprocal space

so I thought the implied meaning of the components was the same as for rhor, a la section 6.5 of the abinit help file... but this is not the case? For example, then there is no spin dependence in the fourier components of rho?

Otherwise is the indexing of rhog analagous to that of rhor? I.e., if I have reciprocal lattice vectors {Q_1, Q_2, Q_3}, then:
rhog(1,1) is the real part of the g=0 component; rhog(1,2) is the real part of the g=Q_1 component; rhog(1,3) is the real part of the
g=2Q_1 component; and so on up to ifft=ngfft(1)? And the at ifft=ngfft(1)+1 rhog(1,ifft) is the real part of the g=Q_2 component; and the next index is the g=Q_1+Q_2 component, and next 2*Q_1+Q_2 components, and so on similarly to the indexing of rhor?

Thanks very much,

Adam
 

About getting rhog without modifying the code... I don't know if this
is possible however the modification would be quite light if nobody
did it before. for instance,  you can just  find the routine that
print rhor and provide it rhog instead ...

regards

PMA

On Fri, May 23, 2008 at 9:44 AM,  <asorini@gmail.com> wrote:
> Hi,
>
>  I've searched through the archive for a response to this question, but I can't
> seem to find one. I've found one person who asked the same question in 2003,
> but it seems to have never been answered.
>
> Anyways, my question is about rhog, the Fourier components of rhor. I've been
> able to print out rhog by adding a line of code to one of the outscf
> subroutines. I've checked that the g=zero component (the component
> corresponding to index=1) gives the average electronic number density, but I'm
> a little confused as to the other components. In a general system (without
> inversion point?) rhog should be complex, but in ABINIT rhog looks to be a
> real. How is this possible?
>
> Also, is there a way to get rhog output from ABINIT without modifying the code?
> As an option for prtden card? I didn't think so, but maybe it is a secret.
>
> Also, I am confused about the indexing of rhog. Originally I would have thought
> that the indexing of rhog works the same as for rhor, but in reciprocal
> space... but since the rhog variable is real and not complex in ABINIT I'm not
> sure if this is the case... Has anyone else looked into this or is anyone able
> to offer advice? thanks in advance.
>
> Adam
>

--
Pierre-Matthieu Anglade