[Pw_forum] NiMnSb calculations

[Maria Peressi]

Dear dr. K. Ramesh Kumar,

since in your input file I read nelec=22, I suppose you are using 
different pseudopotentials:
we used for instance 15 valence electrons for Mn (3s and 3p in valence 
- see the cited paper),
therefore we have much more electrons and hence more bands than you 
have; this could explain
at least why your bands "are concentrated within 5 ev".
Regards

Maria Peressi

On Aug 27, 2008, at 11:32 AM, ramesh kumar wrote:

>
>
>  Dear all and  Dr. Alberto Debernardi
>
>  i am learning band structure for half metallic ferromagnets. To start 
> with i am trying to do for NiMnSb (debernardi etal Volume 23, Issues 
> 6-8, 15 December 2003, Pages 743-746). i used the same pseudo 
> potential and k_points grid but i am not able to reproduce the band 
> structure.
>
>  the problems i faced
>
>  1. fluctuations in the convergence (despite 20%  increase of the # of 
> bands)
>  2. all the bands are concentrated within 5 ev which is different from 
> the Dr. Alberto paper.
>
>  3. i got half-metallic gap of ~ 1.2 ev
>
>  i dont know whether i am going in the right direction.
>
>  Here with i am giving the input file plz correct me if i had 
> committed blunders in the input file.
>  &control
>      calculation='scf'
>      restart_mode='from_scratch',
>      pseudo_dir = '/usr/local/espresso-3.2.3/pseudo/',
>      outdir='/home/mmm-lab/tmp/'
>      prefix='nimnsb-example'
>     
>  /
>  &system
>      ibrav=2, celldm(1) =10.77, nat=3, ntyp=3,
>      nspin = 2, ecutwfc = 35.0, ecutrho = 560.0, nelec=22, 
> tot_magnetization=4,
>      occupations='smearing', smearing='methfessel-paxton', degauss=0.02
>  /
>  &electrons
>      diagonalization='david'
>      conv_thr = 1.0e-6
>      mixing_beta = 0.7
>  /
>  ATOMIC_SPECIES
>  Ni 58.69  Ni_ps.uspp.UPF
>  Mn 54.93  Mn_KB_LDA.uspp.UPF
>  Sb 121.76 Sb.pz-bhs.UPF
>
>  ATOMIC_POSITIONS
>  Mn 0.25 0.25 0.25
>  Ni 0.0 0.0 0.0
>  Sb 0.75 0.75 0.75
>  K_POINTS {automatic}
>  8 8 1 0 0 0
>
>  With regards
>
>  K. Ramesh Kumar
>  Research Scholar
>  Department of Physics
>  IIT-Madras
>  Chennai-600 036
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
Maria Peressi
Department of Theoretical Physics
University of Trieste
Strada Costiera 11
I-34014 Trieste
tel. +39 040 2240242
fax. +39 040 224601