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:[email protected]
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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