[Pw_forum] Problem in SCF convergence with larger unit cells
Giuseppe Mattioli
giuseppe.mattioli at ism.cnr.it
Sun Jun 12 11:12:19 CEST 2016
Dear Reza
You can try to use ultrasoft pseudopotentials
you may try these ones you find in the online library
Ga.pbe-dn-rrkjus_psl.0.2.UPF
P.pbe-n-rrkjus_psl.0.1.UPF
But you should check the convergence, and I expect something like
ecutwfc=40.0
ecutrho=320.0~480.0
Best Regards
Giuseppe
Quoting reza vatan <rezavatan64 at gmail.com>:
> Dear Giuseppe,
>
> I had tried the calculations with higher ecutwfc before and as you said it
> perfectly worked. But the problem is that the calculations take much
> longer. Is there any way to keep the ecutwfc as small as possible and use
> different pseudopotentials and still get convergence? Please advise.
>
> Many thanks in advance.
>
> Regards,
> Reza
>
> On Sat, Jun 11, 2016 at 2:21 PM, Giuseppe Mattioli <
> giuseppe.mattioli at ism.cnr.it> wrote:
>
>>
>> Dear Reza Vatan
>>
>> > ecutwfc = 12.0,
>>
>> > Ga 69.72 Ga.blyp-d-hgh.UPF
>> > P 30.97 P.blyp-hgh.UPF
>>
>> It is very strange that you converge at all with a so minimal cutoff
>> and so hard hgh norm-conserving pseudopotentials. I would bet that
>> ecutwfc = 100.0 is barely sufficient for Ga with semicore d shell in
>> valence. I suggest that you raise ecutwfc and find convergence for GaP
>> in the 2 atoms cell.
>> HTH
>> Giuseppe
>>
>> Quoting reza vatan <rezavatan64 at gmail.com>:
>>
>> > Dear all,
>> >
>> > I'm trying to optimize the atomic structure of GaP using QE. When I use a
>> > unit cell only containing two atoms, I have no problem in SCF convergence
>> > and the structure get optimized in the first step. But when I make my
>> unit
>> > cell bigger (let's say a unit cell with 64 atoms) just by repeating my
>> > smaller optimized unit cell in real space and run relax calculation, the
>> > SCF calculation never get converged. Does anyone know where the problem
>> is?
>> >
>> > Following is my input:
>> >
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > &CONTROL
>> > calculation = "relax",
>> > dt = 30.D0,
>> > prefix = 'gap',
>> > pseudo_dir = './',
>> > outdir='./',
>> > /
>> > &system
>> > ibrav= 6, celldm(1) =20.52, celldm(3) =1, nat= 64, ntyp= 2,
>> > ecutwfc = 12.0,
>> > degauss = 0.05D0,
>> > occupations = "fixed",
>> > smearing = "methfessel-paxton",
>> > /
>> > &ELECTRONS
>> > conv_thr = 1.D-7,
>> > mixing_beta = 0.3D0,
>> > electron_maxstep= 200,
>> > /
>> > &IONS
>> > pot_extrapolation = "second_order",
>> > wfc_extrapolation = "second_order",
>> > /
>> > ATOMIC_SPECIES
>> > Ga 69.72 Ga.blyp-d-hgh.UPF
>> > P 30.97 P.blyp-hgh.UPF
>> > ATOMIC_POSITIONS (angstrom)
>> > Ga 2.7146780000 2.7146780000 0.0000000000
>> > Ga 0.0000000000 0.0000000000 0.0000000000
>> > Ga 2.7146780000 0.0000000000 2.7146780000
>> > Ga 0.0000000000 2.7146780000 2.7146780000
>> > P 4.0720170000 4.0720170000 1.3573390000
>> > P 1.3573390000 1.3573390000 1.3573390000
>> > P 4.0720170000 1.3573390000 4.0720170000
>> > P 1.3573390000 4.0720170000 4.0720170000
>> > Ga 2.7146780000 2.7146780000 5.4293560000
>> > Ga 0.0000000000 0.0000000000 5.4293560000
>> > Ga 2.7146780000 0.0000000000 8.1440340000
>> > Ga 0.0000000000 2.7146780000 8.1440340000
>> > P 4.0720170000 4.0720170000 6.7866950000
>> > P 1.3573390000 1.3573390000 6.7866950000
>> > P 4.0720170000 1.3573390000 9.5013730000
>> > P 1.3573390000 4.0720170000 9.5013730000
>> > Ga 2.7146780000 8.1440340000 0.0000000000
>> > Ga 0.0000000000 5.4293560000 0.0000000000
>> > Ga 2.7146780000 5.4293560000 2.7146780000
>> > Ga 0.0000000000 8.1440340000 2.7146780000
>> > P 4.0720170000 9.5013730000 1.3573390000
>> > P 1.3573390000 6.7866950000 1.3573390000
>> > P 4.0720170000 6.7866950000 4.0720170000
>> > P 1.3573390000 9.5013730000 4.0720170000
>> > Ga 2.7146780000 8.1440340000 5.4293560000
>> > Ga 0.0000000000 5.4293560000 5.4293560000
>> > Ga 2.7146780000 5.4293560000 8.1440340000
>> > Ga 0.0000000000 8.1440340000 8.1440340000
>> > P 4.0720170000 9.5013730000 6.7866950000
>> > P 1.3573390000 6.7866950000 6.7866950000
>> > P 4.0720170000 6.7866950000 9.5013730000
>> > P 1.3573390000 9.5013730000 9.5013730000
>> > Ga 8.1440340000 2.7146780000 0.0000000000
>> > Ga 5.4293560000 0.0000000000 0.0000000000
>> > Ga 8.1440340000 0.0000000000 2.7146780000
>> > Ga 5.4293560000 2.7146780000 2.7146780000
>> > P 9.5013730000 4.0720170000 1.3573390000
>> > P 6.7866950000 1.3573390000 1.3573390000
>> > P 9.5013730000 1.3573390000 4.0720170000
>> > P 6.7866950000 4.0720170000 4.0720170000
>> > Ga 8.1440340000 2.7146780000 5.4293560000
>> > Ga 5.4293560000 0.0000000000 5.4293560000
>> > Ga 8.1440340000 0.0000000000 8.1440340000
>> > Ga 5.4293560000 2.7146780000 8.1440340000
>> > P 9.5013730000 4.0720170000 6.7866950000
>> > P 6.7866950000 1.3573390000 6.7866950000
>> > P 9.5013730000 1.3573390000 9.5013730000
>> > P 6.7866950000 4.0720170000 9.5013730000
>> > Ga 8.1440340000 8.1440340000 0.0000000000
>> > Ga 5.4293560000 5.4293560000 0.0000000000
>> > Ga 8.1440340000 5.4293560000 2.7146780000
>> > Ga 5.4293560000 8.1440340000 2.7146780000
>> > P 9.5013730000 9.5013730000 1.3573390000
>> > P 6.7866950000 6.7866950000 1.3573390000
>> > P 9.5013730000 6.7866950000 4.0720170000
>> > P 6.7866950000 9.5013730000 4.0720170000
>> > Ga 8.1440340000 8.1440340000 5.4293560000
>> > Ga 5.4293560000 5.4293560000 5.4293560000
>> > Ga 8.1440340000 5.4293560000 8.1440340000
>> > Ga 5.4293560000 8.1440340000 8.1440340000
>> > P 9.5013730000 9.5013730000 6.7866950000
>> > P 6.7866950000 6.7866950000 6.7866950000
>> > P 9.5013730000 6.7866950000 9.5013730000
>> > P 6.7866950000 9.5013730000 9.5013730000
>> > K_POINTS {automatic}
>> > 2 2 2 0 0 0
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >
>> >
>> > Thanks in advance.
>> >
>> > Regards,
>> > Reza Vatan
>> > School of Electrical, Computer and Energy Engineering
>> > Arizona State University
>>
>>
>> --
>> ********************************************************
>> - Article premier - Les hommes naissent et demeurent
>> libres et égaux en droits. Les distinctions sociales
>> ne peuvent être fondées que sur l'utilité commune
>> - Article 2 - Le but de toute association politique
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>> imprescriptibles de l'homme. Ces droits sont la liberté,
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>> ********************************************************
>>
>> Giuseppe Mattioli
>> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
>> v. Salaria Km 29,300 - C.P. 10
>> I 00015 - Monterotondo Stazione (RM)
>> Tel + 39 06 90672836 - Fax +39 06 90672316
>> E-mail: <giuseppe.mattioli at ism.cnr.it>
>> http://www.ism.cnr.it/en/staff/giuseppe-mattioli/
>> ResearcherID: F-6308-2012
>>
>>
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********************************************************
- Article premier - Les hommes naissent et demeurent
libres et égaux en droits. Les distinctions sociales
ne peuvent être fondées que sur l'utilité commune
- Article 2 - Le but de toute association politique
est la conservation des droits naturels et
imprescriptibles de l'homme. Ces droits sont la liberté,
la propriété, la sûreté et la résistance à l'oppression.
********************************************************
Giuseppe Mattioli
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
v. Salaria Km 29,300 - C.P. 10
I 00015 - Monterotondo Stazione (RM)
Tel + 39 06 90672836 - Fax +39 06 90672316
E-mail: <giuseppe.mattioli at ism.cnr.it>
http://www.ism.cnr.it/en/staff/giuseppe-mattioli/
ResearcherID: F-6308-2012
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