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

[Sheikh Ziauddin Ahmed]

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*@virginia.edu* <sza9wz at virginia.edu>
LinkedIn: https://www.linkedin.com/in/sheikh-ziauddin-ahmed
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