[QE-users] Does order of atoms matter in Quantum Espresso?

[Sheikh Ziauddin Ahmed]

The commented lines are not wanted.

On Mon, Dec 30, 2019 at 5:34 PM Andrea Ferretti <andrea.ferretti at nano.cnr.it>
wrote:

>
> Dear Sheikh Ziauddin Ahmed,
>
> the reordering of the atoms should not have an effect (besides the fact
> ths you are also swapping the coordinates of the two atoms).
> The biggest difference I see here is related to the smearing, which is
> commented in the second input.
>
> >     !occupations='smearing',
> >     !smearing='gauss',
> >     !degauss=0.05,
>
> Is this wanted ?
> (BTW: gaussian smearing of 0.05 Ry seems quite large to me)
>
> take care
> Andrea
>
> > I am trying to calculate the phonon dispersion of AlSb. I am getting two
> different results depending on how I am introducing the atoms in the
> > SCF calculation. Will the order of the atom change the symmetry of the
> zinc blende AlSb?
> > In the first case the input deck is:
> > &system
> >     ibrav=2, nat=2, ntyp=2,
> >     ecutwfc = 50, ecutrho = 500,
> >     occupations='smearing',
> >     smearing='gauss',
> >     degauss=0.05,
> >     celldm(1)=11.5944146,
> >  /
> >  &electrons
> >     conv_thr    = 1.0e-12
> >     mixing_beta = 0.7
> >     mixing_mode = 'local-TF'
> >  /
> > ATOMIC_SPECIES
> >  Al 26.98 al_lda_v1.uspp.F.UPF
> >  Sb 121.76 sb_lda_v1.4.uspp.F.UPF
> > ATOMIC_POSITIONS (alat)
> >  Al 0.0   0.0   0.0
> >  Sb 0.25  0.25  0.25
> > K_POINTS automatic
> > 6 6 6 0 0 0
> >
> > In the second case the input deck is:
> >  &system
> >     ibrav=2, nat=2, ntyp=2,
> >     ecutwfc = 50, ecutrho = 500,
> >     !occupations='smearing',
> >     !smearing='gauss',
> >     !degauss=0.05,
> >     celldm(1)=11.5944146,
> >  /
> >  &electrons
> >     conv_thr    = 1.0e-12
> >     mixing_beta = 0.7
> >     mixing_mode = 'local-TF'
> >  /
> > ATOMIC_SPECIES
> >  Sb 121.76 sb_lda_v1.4.uspp.F.UPF
> >  Al 26.98 al_lda_v1.uspp.F.UPF
> > ATOMIC_POSITIONS (alat)
> >  Sb 0.0   0.0   0.0
> >  Al 0.25  0.25  0.25
> > K_POINTS automatic
> > 6 6 6 0 0 0
> >
> > Thanks in advance!
> > --
> > Sheikh Ziauddin Ahmed
> > PhD Candidate
> > Charles L. Brown Department of Electrical and Computer Engineering
> > University of Virginia
> > Email:sza9wz at virginia.edu
> > LinkedIn: https://www.linkedin.com/in/sheikh-ziauddin-ahmed
> >
> >
>
> --
> Andrea Ferretti, PhD
> S3 Center, Istituto Nanoscienze, CNR
> via Campi 213/A, 41125, Modena, Italy
> Tel: +39 059 2055322;  Skype: andrea_ferretti
> URL: http://www.nano.cnr.it
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-- 
*Sheikh Ziauddin Ahmed *
PhD Candidate
Charles L. Brown Department of Electrical and Computer Engineering
University of Virginia
Email:sza9wz*@virginia.edu* <sza9wz at virginia.edu>
LinkedIn: https://www.linkedin.com/in/sheikh-ziauddin-ahmed
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