The ABINIT Users Mailing List ( CLOSED )

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

On Sat, May 24, 2008 at 4:02 AM, Anglade Pierre-Matthieu <anglade@gmail.com> wrote:

Hi,

It is quite possible that :
1 ) someone  mistakes in a comment and possibly also in some part of the code
2 ) something else is called rhog ...
3) other ? Where did you found this comment ?

it was in abinit-5.2. I found it in abinit-5.2.4/src/11drive/outscfcv.F90 comments at begining of file.

thanks for the other pointers. they seem very helpful. cheers,

adam
 

However the definition I took for rhog is that used in the main
density evaluation routine : mkrho
(http://www.abinit.org/package/robodoc/15common/mkrho_F90.html#robo731)

About nfft : did you already find the documentation of this word
(http://www.abinit.org/Infos_v5.5/input_variables/varint.html#nfft) ?

Also there is some routines that computes the G vector associated with
each component. I can't remember their name but here is the one I
wrote, from them, that compute G^2
http://www.abinit.org/package/robodoc/13recipspace/laplacian_F90.html#robo_top_of_doc

regards

PMA

On Sat, May 24, 2008 at 2:25 AM, Adam Sorini <asorini@gmail.com> wrote:
> On Fri, May 23, 2008 at 4:51 PM, Adam Sorini <asorini@gmail.com> wrote:
>>
>> 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?
>
> actually, after a bit more looking around I see that there is also a rhogsp
> variable which, I presume, may be used for spin dependent calculations.
>
> so, now my only confusion is about how exactly the ifft index on rhog works.
> Any help in this regard would be much appreciated.
>
> Cheers,
>
> adam
>
>>
>> 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
>>
>
>

--
Pierre-Matthieu Anglade