[QE-users] Crystal structure changes while doing vc-relax calculation.

Vivek Christhunathan vivekppn at gmail.com
Thu Feb 3 15:05:56 CET 2022


Hello Everyone,

I could not solve this issue even after trying with v6.8 (the older version
was v6.4.1). Still, the CaWO4 (2x1x1 supercell) changes its symmetry
from Tetragonal
to Orthorhombic while doing structural relaxation. Even I tried with
multiple different input parameters.

Can I get any suggestions regarding this, please?

Kind Regards,

Vivek C


__________________________________

Vivek Christhunathan

PhD researcher

Mechanical Engineering

College of Engineering and Informatics

Room 2053

Alice Perry Engineering Building

National University of Ireland Galway

Ireland
E-mail: v.christhunathan1 at nuigalway.ie
Phone: +353 899811181, +91 9600752742



On Tue, Feb 1, 2022 at 12:52 PM Vivek Christhunathan <vivekppn at gmail.com>
wrote:

> Hello Everyone,
>
> I'm bringing attention to a topic that has previously been discussed in
> this forum. I too faced the same type of problem when I try to do
> structural relaxation for CaWO4 (2x1x1 supercell), that its crystal
> structure changed from Tetragonal to Orthorhombic. I tried all the
> following forum's suggestions to get rid of this problem.
>
> As per their suggestion, I tried using the following tags in my input file,
>
>
>
>
> *>ion_dynamics = 'damp'>and>cell_dynamics = "damp-pr">which should respect
> the constraint.*
>
> And also I tried using *cell_dofree=‘ibrav'*. but still lattice parameter
> values a and b are not the same. Still, its structure changes from
> Tetragonal to Orthorhombic.
>
>
>
>
>
> *>You can open Modules/cell_base.f90 and at line 84 change>LOGICAL   ::
> enforce_ibrav = .FALSE.! True if ibrav ...>to>LOGICAL   :: enforce_ibrav =
> .TRUE.! True if ibrav ...>(do not forget to recompile pw.x) to use
> cell_dofree="ibrav" together with any >other cell_dofree*
>
> Since I'm utilizing the Government's supercomputer cluster, I'm not sure
> how I'd make these adjustments to the QE code. Can I get your suggestion
> regarding this?
>
>
>
> *>Should be present in the available patches for v.6.4.1:
> filebackports-6.4.1.diff*
>
> <https://github.com/QEF/q-e/releases/download/qe-6.4.1/backports-6.4.1.diff>
> in https://github.com/QEF/q-e/releases
>
>
> Could you please advise me on how to proceed with this link?
>
> I have included calculations input and output for your perusal.
>
> If you could share your thoughts on this issue, that would be quite
> helpful.
>
> *Input:*
>
> &control
> calculation = 'vc-relax'
> restart_mode = 'restart'
> prefix = 'CaWO4'
> tstress = .true.
> tprnfor = .true.
> pseudo_dir = './'
> outdir = './outCaWO4'
> wf_collect=.true.
> forc_conv_thr = 1d-4
> etot_conv_thr = 1D-4
> !disk_io = 'medium'
> max_seconds = 7200,
> /
>
> &system
> ibrav = 0
> *celldm(1) = 19.820415*
> nat = 48
> ntyp = 3
> ecutwfc = 65.0
> ecutrho = 780.0
> occupations= 'smearing'
> smearing= 'gaussian'
> degauss= 0.02
> /
>
> &electrons
> mixing_beta = 0.2,
> conv_thr = 1.0d-6,
> electron_maxstep = 50000,
> /
>
> &IONS
> *ion_dynamics = 'damp'*
>
> /
>
> &cell
> cell_factor = 3.0d0
> *cell_dynamics = 'damp-pr'*
> !cell_dofree= 'ibrav'
> /
>
> ATOMIC_SPECIES
>  Ca 40.08   Ca.pbe-spn-rrkjus_psl.1.0.0.UPF
>  W  183.84  W.pbe-spn-rrkjus_psl.1.0.0.UPF
>  O  16.00   O.pbe-n-rrkjus_psl.1.0.0.UPF
>
> *CELL_PARAMETERS (alat)*
> *        1.0000000000         0.0000000000         0.0000000000*
> *        0.0000000000         0.4999999999         0.0000000000*
> *        0.0000000000         0.0000000000         1.0845493931*
>
> ATOMIC_POSITIONS (crystal)
> Ca     0.000000000         0.250000000         0.625000000
> Ca     0.500000000         0.250000000         0.625000000
> Ca     0.000000000         0.750000000         0.375000000
> Ca     0.500000000         0.750000000         0.375000000
> Ca     0.250000000         0.750000000         0.125000000
> Ca     0.750000000         0.750000000         0.125000000
> Ca     0.250000000         0.250000000         0.875000000
> Ca     0.750000000         0.250000000         0.875000000
>  W     0.000000000         0.250000000         0.125000000
>  W     0.500000000         0.250000000         0.125000000
>  W     0.000000000         0.750000000         0.875000000
>  W     0.500000000         0.750000000         0.875000000
>  W     0.250000000         0.750000000         0.625000000
>  W     0.750000000         0.750000000         0.625000000
>  W     0.250000000         0.250000000         0.375000000
>  W     0.750000000         0.250000000         0.375000000
>  O     0.074850000         0.009300000         0.209700003
>  O     0.574850023         0.009300000         0.209700003
>  O     0.425150007         0.990700006         0.790300012
>  O     0.925150037         0.990700006         0.790300012
>  O     0.175150007         0.990700006         0.709699988
>  O     0.675150037         0.990700006         0.709699988
>  O     0.324849993         0.009300000         0.290300012
>  O     0.824849963         0.009300000         0.290300012
>  O     0.370350003         0.399699986         0.459699988
>  O     0.870350003         0.399699986         0.459699988
>  O     0.129649997         0.600300014         0.540300012
>  O     0.629649997         0.600300014         0.540300012
>  O     0.379649997         0.600300014         0.959699988
>  O     0.879649997         0.600300014         0.959699988
>  O     0.120350003         0.399699986         0.040299997
>  O     0.620350003         0.399699986         0.040299997
>  O     0.324849993         0.509299994         0.709699988
>  O     0.824849963         0.509299994         0.709699988
>  O     0.175150007         0.490700006         0.290300012
>  O     0.675150037         0.490700006         0.290300012
>  O     0.425150007         0.490700006         0.209700003
>  O     0.925150037         0.490700006         0.209700003
>  O     0.074850000         0.509299994         0.790300012
>  O     0.574850023         0.509299994         0.790300012
>  O     0.120350003         0.899699986         0.959699988
>  O     0.620350003         0.899699986         0.959699988
>  O     0.379649997         0.100299999         0.040299997
>  O     0.879649997         0.100299999         0.040299997
>  O     0.129649997         0.100299999         0.459699988
>  O     0.629649997         0.100299999         0.459699988
>  O     0.370350003         0.899699986         0.540300012
>  O     0.870350003         0.899699986         0.540300012
>
> K_POINTS AUTOMATIC
> 2 2 2 1 1 1
>
> *Output (a scf loop from output file):*
>
>  atom   48 type  3   force =     0.00003185   -0.00002222   -0.00008890
>
>      Total force =     0.000633     Total SCF correction =     0.000137
>      SCF correction compared to forces is large: reduce conv_thr to get
> better values
>
>
>      Computing stress (Cartesian axis) and pressure
>
>
>      negative rho (up, down):  1.178E+00 0.000E+00
>           total   stress  (Ry/bohr**3)                   (kbar)     P=
>   0.04
>    0.00000050  -0.00000019  -0.00000004          0.07     -0.03     -0.01
>   -0.00000019   0.00000058  -0.00000002         -0.03      0.08     -0.00
>   -0.00000004  -0.00000002  -0.00000017         -0.01     -0.00     -0.02
>
>
>      number of scf cycles    =  14
>      number of bfgs steps    =  13
>
>      enthalpy old            =   -2905.7085634122 Ry
>      enthalpy new            =   -2905.7085638929 Ry
>
>      CASE: enthalpy_new < enthalpy_old
>
>      new trust radius        =       0.0005206840 bohr
> WARNING! With ibrav=0, cell_dofree='ibrav' does not have any effect.
>      new conv_thr            =       0.0000000100 Ry
>
>      new unit-cell volume =   4353.65352 a.u.^3 (   645.14488 Ang^3 )
>      density =      5.92862 g/cm^3
>
> *CELL_PARAMETERS (alat= 19.82041500)*
> *   1.009431575   0.000035319   0.000001684*
> *   0.000017655   0.504836574   0.000001702*
> *   0.000001845   0.000003719   1.097205402*
>
> ATOMIC_POSITIONS (crystal)
> Ca       0.000001762   0.249997612   0.625000246
> Ca       0.500002903   0.249995682   0.624999551
> Ca      -0.000001762   0.750002388   0.374999754
> Ca       0.499997097   0.750004318   0.375000449
> Ca       0.249995760   0.750002886   0.125000569
> Ca       0.749997044   0.750001219   0.124998286
> Ca       0.250002956   0.249998781   0.875001714
> Ca       0.750004240   0.249997114   0.874999431
> W       -0.000007775   0.250005618   0.125011626
> W        0.499993856   0.250003532   0.125006749
> W        0.000007775   0.749994382   0.874988374
> W        0.500006144   0.749996468   0.874993251
> W        0.250000614   0.749987294   0.625009963
> W        0.750012640   0.750006266   0.625006514
> W        0.249987360   0.249993734   0.374993486
> W        0.749999386   0.250012706   0.374990037
> O        0.074741741   0.007038639   0.209937560
> O        0.574740434   0.007045102   0.209936159
> O        0.425259596   0.992954904   0.790063856
> O        0.925258296   0.992961367   0.790062455
> O        0.175252613   0.992959249   0.709941460
> O        0.675260736   0.992953207   0.709933905
> O        0.324739294   0.007046799   0.290066095
> O        0.824747357   0.007040757   0.290058540
> O        0.371508681   0.399412719   0.459931561
> O        0.871509937   0.399409012   0.459929597
> O        0.128490063   0.600590988   0.540070403
> O        0.628491319   0.600587281   0.540068439
> O        0.378491935   0.600589896   0.959931149
> O        0.878493035   0.600590218   0.959930080
> O        0.121506965   0.399409782   0.040069905
> O        0.621508065   0.399410104   0.040068836
> O        0.324753467   0.507030327   0.709936158
> O        0.824758249   0.507031484   0.709937563
> O        0.175241721   0.492968516   0.290062437
> O        0.675246563   0.492969673   0.290063842
> O        0.425243174   0.492974405   0.209938014
> O        0.925241517   0.492963083   0.209937166
> O        0.074758520   0.507036917   0.790062849
> O        0.574756856   0.507025595   0.790062001
> O        0.121518578   0.899409145   0.959930613
> O        0.621518989   0.899409438   0.959931475
> O        0.378481011   0.100590547   0.040068510
> O        0.878481422   0.100590840   0.040069372
> O        0.128480180   0.100591392   0.459933045
> O        0.628486141   0.100588990   0.459929416
> O        0.371513859   0.899410995   0.540070584
> O        0.871519820   0.899408593   0.540066955
>
>
>
>      Writing output data file CaWO4.save/
>      NEW-OLD atomic charge density approx. for the potential
>
>      negative rho (up, down):  1.178E+00 0.000E+00
>      extrapolated charge  384.00680, renormalised to  384.00000
>
>      total cpu time spent up to now is     3371.9 secs
>
>      Self-consistent Calculation
>
>      iteration #  1     ecut=    65.00 Ry     beta= 0.20
>      Davidson diagonalization with overlap
>      ethr =  1.00E-06,  avg # of iterations =  2.0
>
>
> Thanks in advance.
>
> Kind Regards,
>
> Vivek C
>
>
> __________________________________
>
> Vivek Christhunathan
>
> PhD researcher
>
> Mechanical Engineering
>
> College of Engineering and Informatics
>
> Room 2053
>
> Alice Perry Engineering Building
>
> National University of Ireland Galway
>
> Ireland
> E-mail: v.christhunathan1 at nuigalway.ie
> Phone: +353 899811181, +91 9600752742
>
>
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