Hi
The problem of integration or population analysis is a common problem in PW
codes and for solids in general. Since the "idea" of atomic-like orbital
doesn't have sense anymore, and a band-like concepts is the important one.
The integration around and mt-sphere is just for having a rough idea about
local magnetic moments, and the "observable" magnitude is just the Qup-Qdn in
cell. However I remember a paper from P.Novak where he studied the local
magnetic moment (using Wien2k) first in the muffin-tin (MT) sphere, and then He
extrapolate this value according with percentage of radial
3d-isolated-atomic-orbital.
MagneticMoment=MM(muffin-tin-sphere)*area(3d-isolated-atomic-orbital between
r=0 - infinity)/area(3d-isolated-atomic-orbital between r=0 - MT radius)
Regards
Ricardo
-------------------------------------------------------------------------
----- Ing. Quím. Ricardo Faccio
Mail: Cryssmat-Lab., Cátedra de Física, DETEMA
Facultad de Química, Universidad de la República
Av. Gral. Flores 2124, C.C. 1157
C.P. 11800, Montevideo, Uruguay.
E-mail: [EMAIL PROTECTED]
Phone: 598 2 9241860 Int. 109
598 2 9290705
Fax: 598 2 9241906
Web: http://cryssmat.fq.edu.uy/ricardo/ricardo.htm
----- Original Message -----
From: Vasilii Artyukhov
To: SIESTA-L@listserv.uam.es
Sent: Tuesday, April 24, 2007 8:01 AM
Subject: Re: [SIESTA-L] A question about local magnetic moment
Hi Marcos,
Yes, the arbitrariness of radius choice is exactly what I'm talking about.
There's a strict way to choose the integration region using the geometrical
properties of the density. I'm not very aware about the details or what codes
can do it. If someone's interested in having a postprocessing tool for such an
analysis, I could look it up in more detail.
2007/4/24, Marcos Verissimo Alves <[EMAIL PROTECTED]>:
Hi Vasilii,
I guess so. I remember one of the e-mails of the list, in which Emilio
talks about the calculation of PDOS in siesta. Since it is mulliken-like
in nature, it would depend on the basis set as well. However, the
integration over atomic spheres is what makes me a bit worried on
practical aspects: how to choose the sphere radius? Although it would have
the advantage of being effectively independent of the basis set, as you
say, I don't see, in principle, a reasonable way of choosing the radii.
Maybe there is, but I really can't think, at the moment, of any reasonable
way. Any tips?
Marcos
> Dear Marcos,
>
> It seems like a very nice idea, but doesn't PDOS depend strongly on the
> basis set, as well? I still think that the most reliable choice would be
> to
> work directly with the total spin density.
>
> 2007/4/23, Marcos Verissimo Alves <[EMAIL PROTECTED]>:
>>
>> This question has just come to discussion on the list in the last few
>> days... Using the mulliken populations would be one way of doing it.
>> Another would be to use Andrei Postnikov's tools for integration of
>> charge
>> density over atomic spheres. Yet another way would be to calculate the
>> PDOS for each atom with a small smearing, then integrate over the
>> energies
>> up to the Fermi level. Seems complicated but with some shell scripting,
>> sed and a small fortran/c program to integrate the PDOS it can be
>> accomplished without too much difficulty.
>>
>> Cheers,
>>
>> Marcos
>>
>>
>> > Is it right if only use the value of "SPIN-UP - SPIN-DOWN" in Mulliken
>> > population analysis?
>> >
>> >> Dear Siesta usrers,
>> >>
>> >> How to get the local magnetic moment of each atom in the clusters,
>> >> molecules, or solids using siesta code?
>> >>
>> >> Best regards,
>> >> C. H. Hu
>> >>
>> >>
>> >
>> >
>>
>>
>> --
>> Dr. Marcos Verissimo Alves
>> Post-Doctoral Fellow
>> Condensed Matter and Statistical Physics Sector
>> International Centre for Theoretical Physics
>> Trieste, Italy
>>
>> --------
>>
>> I have become so addicted to vi that I try to exit OpenOffice by typing
>> :wq!
>>
>
--
Dr. Marcos Verissimo Alves
Post-Doctoral Fellow
Condensed Matter and Statistical Physics Sector
International Centre for Theoretical Physics
Trieste, Italy
--------
I have become so addicted to vi that I try to exit OpenOffice by typing :wq!
