Dear Giovani
I personnaly did calculations on Fe clusters some time ago. I always found
"almost integer" magnetic moments.
However I once encoutered some difficulties with the default value of "nbnd".
I had to increase it. Try to set nbnd=20 for example...
Magnetic clusters can be very tricky.. It also very common to find several
magnetic solutions..
good luck
cyrille
==================================================================
Cyrille Barreteau phone :
+33 (0)1 69 08 29 51
CEA Saclay fax :
+33 (0)1 69 08 84 46
IRAMIS, SPCSI, Batiment 462 email
cyrille.barreteau at cea.fr
91191 Gif sur Yvette Cedex
FRANCE
~~~~~~~~~~~~~~~~~~~~~~~~
Web: http://iramis.cea.fr/Pisp/cyrille.barreteau/
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________________________________
De: pw_forum-bounces at pwscf.org de la part de Giovani Faccin
Date: lun. 14/02/2011 05:50
?: PWSCF Forum
Objet : Re: [Pw_forum] RE : A question on atomic magnetic moments
Dear Cyrille,
First of all, thanks for the reply on my post.
Following your suggestion, I've run a few calculations with lower degauss
values. In particular, the ones reported on the message for Duy Le were made
with a much smaller value ( 0.005 ) than the original 0.02 from the first
message. Besides that, I've tried degauss values as low as 0.002 without any
significant improvement on the final magnetization.
I'm still wondering how do people find 6.00 so easily for the magnetization.
I'm trying with 2 different DFT codes and no way I'm reaching those results,
even though bulk/dimer equilibrium distances and force constants appear to be
ok.
Any other ideas, just tell me, I'll try it and report back on the list.
Thanks again,
Giovani
2011/2/13 BARRETEAU Cyrille <cyrille.barreteau at cea.fr>
Dear Giovani
Try to decrease the degauss value of your smearing.. and see what
happens.
cyrille
==================================================================
Cyrille Barreteau
phone : +33 (0)1 69 08 29 51
CEA Saclay
fax : +33 (0)1 69 08 84 46
IRAMIS, SPCSI, Batiment 462 email
cyrille.barreteau at cea.fr
91191 Gif sur Yvette Cedex
FRANCE
~~~~~~~~~~~~~~~~~~~~~~~~
Web: http://iramis.cea.fr/Pisp/cyrille.barreteau/
==================================================================
________________________________
De: pw_forum-bounces at pwscf.org de la part de Giovani Faccin
Date: dim. 13/02/2011 07:16
?: PWSCF Forum
Objet : Re: [Pw_forum] A question on atomic magnetic moments
Dear Paolo,
Thanks for the reply.
Just to make sure that the simulation cell size is not an issue (so
that the system is really finite), I've tested different possibilities,
including some quite big cells. Still, after a certain size the value of the
magnetization is converging to 6.82 instead of the expected 6.
So something else is causing this. Unfortunately I've got no clue as to
what could it be.
Should it be of any help, this is my input file:
&CONTROL
calculation = 'scf' ,
restart_mode = 'from_scratch' ,
wf_collect = .true. ,
outdir = './output' ,
pseudo_dir = '../pseudo/' ,
prefix = 'fe' ,
etot_conv_thr = 1.0D-9 ,
forc_conv_thr = 1.0D-6 ,
tstress = .true. ,
tprnfor = .true. ,
/
&SYSTEM
ibrav = 1,
celldm(1) = 43,
nat = 2,
ntyp = 1,
ecutwfc = 100 ,
ecutrho = 300 ,
occupations = 'smearing' ,
degauss = 0.02 ,
smearing = 'methfessel-paxton' ,
nspin = 2 ,
starting_magnetization(1) = 1.0,
/
&ELECTRONS
conv_thr = 1.0e-9 ,
mixing_beta = 0.7 ,
diagonalization = 'david' ,
/
ATOMIC_SPECIES
Fe 58.69000 Fe.pbe-nd-rrkjus.UPF
ATOMIC_POSITIONS angstrom
Fe 0.000000000 0.000000000 0.000000000
Fe 2.047510 0.000000000 0.000000000
K_POINTS automatic
1 1 1 1 1 1
Any suggestions are highly welcome.
Giovani
2011/2/12 Paolo Giannozzi <giannozz at democritos.it>
On Feb 11, 2011, at 17:09 , Giovani Faccin wrote:
> My question: shouldn't those numbers be integers?
only in finite systems, if you neglect spin-orbit.
P.
---
Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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