[QE-users] Does order of atoms matter in Quantum Espresso?
Sheikh Ziauddin Ahmed
sza9wz at virginia.edu
Mon Jan 6 02:26:21 CET 2020
Thanks. I am trying to calculate the phonon dispersion of a superlattice
consisting of InAs and AlSb. However, I am ending up with negative phonon
frequencies for the structure. I used the epsil flag. But that did not
help. How I can eliminate the negative phonon modes?
For relaxation I am using the following input:
&control
calculation='vc-relax'
restart_mode='from_scratch',
prefix='AlInAsSb'
tstress = .true. ,
tprnfor = .true. ,
verbosity ='high'
etot_conv_thr=1.0D-12
forc_conv_thr=1.0D-7
/
&system
ibrav=0, nat=10, ntyp=4,
ecutwfc = 50, ecutrho = 500
/
&electrons
electron_maxstep=1000
conv_thr = 1.0e-9
mixing_beta = 0.7
mixing_mode = 'local-TF'
/
/
&IONS
/
&CELL
cell_dofree = 'z'
/
ATOMIC_SPECIES
Sb 121.76 Sb.pz-n-rrkjus_psl.1.0.0.UPF
Al 26.98 Al.pz-n-rrkjus_psl.0.1.UPF
As 74.92 As.pz-n-rrkjus_psl.0.2.UPF
In 114.82 In.pz-dn-rrkjus_psl.0.2.2.UPF
ATOMIC_POSITIONS {angstrom}
Sb 0.00000000 0.00000000 0.00000000
Sb 0.00000000 3.04570000 3.07106916
Sb 0.00000000 0.00000000 6.14213831
Al 1.52285000 1.52285000 1.53553458
Al -1.52285000 1.52285000 4.60660373
Al 1.52285000 1.52285000 7.67767289
As 0.00000000 3.04570000 9.21320747
As 0.00000000 0.00000000 12.24743004
In -1.52285000 1.52285000 10.73031875
In 1.52285000 1.52285000 13.76454133
K_POINTS automatic
6 6 6 0 0 0
CELL_PARAMETERS {angstrom}
3.0457000000 3.0457000000 0.0000000000
-3.0457000000 3.0457000000 0.0000000000
0.0000000000 0.0000000000 15.2816526121
For SCF run:
&control
calculation='scf'
restart_mode='from_scratch',
tstress = .true. ,
tprnfor = .true. ,
/
&system
ibrav=0, nat=10, ntyp=4,
ecutwfc = 50, ecutrho = 500
/
&electrons
conv_thr = 1.0e-9
mixing_beta = 0.7
mixing_mode = 'local-TF'
/
ATOMIC_SPECIES
Sb 121.76 Sb.pz-n-rrkjus_psl.1.0.0.UPF
Al 26.98 Al.pz-n-rrkjus_psl.0.1.UPF
As 74.92 As.pz-n-rrkjus_psl.0.2.UPF
In 114.82 In.pz-dn-rrkjus_psl.0.2.2.UPF
ATOMIC_POSITIONS {angstrom}
Sb 0.000000000 0.000000000 0.280559797
Sb 0.000000000 3.045700000 3.229150822
Sb 0.000000000 0.000000000 6.101422626
Al 1.522850000 1.522850000 1.784998522
Al -1.522850000 1.522850000 4.668823707
Al 1.522850000 1.522850000 7.525405573
As 0.000000000 3.045700000 8.683670011
As 0.000000000 0.000000000 11.527025485
In -1.522850000 1.522850000 10.092147868
In 1.522850000 1.522850000 13.117431792
K_POINTS automatic
6 6 6 0 0 0
CELL_PARAMETERS {angstrom}
3.045700000 3.045700000 0.000000000
-3.045700000 3.045700000 0.000000000
0.000000000 0.000000000 14.843532218
On Thu, Jan 2, 2020 at 3:54 PM Paolo Giannozzi <p.giannozzi at gmail.com>
wrote:
> On Mon, Dec 30, 2019 at 11:08 PM Sheikh Ziauddin Ahmed <
> sza9wz at virginia.edu> wrote:
>
> 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?
>>
>
> no. See attached.
>
> PG
>
>
>> 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
>> _______________________________________________
>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
>> users mailing list users at lists.quantum-espresso.org
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>
>
>
> --
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
>
--
*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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