[QE-users] CuO relaxation problem

[Mona Asadinamin]

Dear Yue-Wen;

I do not understand what you mean by "method". Could you please clarify?
If you mean the Pseudopotential, I have tried PAW-PBE as well and the results do not improve.

About the convergence thresholds, I have tested tighter force, total energy and scf thresholds, but the results are exactly the same.

I have also increased my ecut and points to 70 and 888, respectively, but again no improvement.

Regarding your comment about smearing, we can not set the initial magnetization without smearing.


Best regards;

Mona Asadi Namin
Graduate student
Center for simulational physics
University of Georgia
--------------------------------------
Email:mona.a at uga.ed<mailto:mona.a at uga.edu>u<mailto:mona.a at uga.edu>


Hello, Mona,

The calculation methods are not as same as the original paper although you
claimed they were the same. The energy convergence criterion you used was
very loose for such a 8-atom cell. Try to improve the convergence accuracy
of the energy and forces. If your convergence criterion is too low, the
structure may be convergence to a seemingly stable phase and it's not
correct. One more comment: because the code in the original paper is not
QE, you may test more, e.g. kmesh, conv_thr.  In addition, for an insulator
with a gap, you can consider using smearing='fixed' to reduce the cost of
calculation.


Mona Asadinamin <Mona.a at uga.edu> ?2020?7?13??? ??10:15???

> Dear QE users and developers;
>
> I have been trying  to relax Tenorite (CuO) with monoclinic structure.
> During relaxation, *the cell parameters change significantly* and *the
> final result is not consistent with the literature*. (Please see TABLE II
> in this paper:
> https://journals.aps.org/prb/abstract/10.1103/PhysRevB.99.035154)
>
> I am using the same parameters for my calculations as in the paper; here
> is my input:
>
>
> &CONTROL
>
>   calculation='vc-relax',
>
>   outdir='.',
>
>   prefix='pw-paperlike',
>
>   pseudo_dir='/home/ma36813/all_pbe_UPF_v1.5',
>
>   verbosity='high',
>
>   etot_conv_thr=1d-05
>
> /
>
>
> &SYSTEM
>
>   ibrav=0,
>
>   celldm(1)=5.4811209354d0,
>
>   nat=8,
>
>   ntyp=3,
>
>   ecutwfc=50,
>
>   ecutrho=500,
>
>   occupations='smearing',
>
>   smearing='mv',
>
>   degauss=0.005d0,
>
>   nspin=2,
>
>   starting_magnetization(1)=0.5,
>
>   starting_magnetization(2)=-0.5,
>
>   vdw_corr='grimme-d3',
>
> /
>
>
> &ELECTRONS
>
>   conv_thr=1d-08,
>
>   mixing_beta=0.7d0,
>
> /
>
> &IONS
>
> /
>
> &CELL
>
> /
>
>
> ATOMIC_SPECIES
>
> Cu1 63.546000d0 cu_pbe_v1.2.uspp.F.UPF
>
> Cu2 63.546000d0 cu_pbe_v1.2.uspp.F.UPF
>
> O 15.999400d0 o_pbe_v1.2.uspp.F.UPF
>
>
> ATOMIC_POSITIONS {crystal}
>
>   Cu1   0.0000000000d0   0.2500000000d0   0.0000000000d0
>
>   Cu2   0.0000000000d0   0.7500000000d0   0.0000000000d0
>
>   Cu2   0.5000000000d0   0.0000000000d0   0.5000000000d0
>
>   Cu1  0.5000000000d0   0.5000000000d0   0.5000000000d0
>
>    O  -0.4184000000d0   0.2092000000d0   0.2500000000d0
>
>    O  -0.4184000000d0   0.7092000000d0   0.2500000000d0
>
>    O   0.4184000000d0  -0.2092000000d0   0.7500000000d0
>
>    O   0.4184000000d0   0.2908000000d0   0.7500000000d0
>
>
> K_POINTS {automatic}
>
>   5 5 5 1 1 1
>
>
> CELL_PARAMETERS {alat}
>
>   0.807399649995d0  -0.590004919630d0  0.000000000000d0
>
>   1.614799299990d0  1.180009839261d0  0.000000000000d0
>
>   -0.293063818044d0  0.000000000000d0  1.743801894963d0
>
>
>
> *Please note that CuO is antiferromagnetic so it requires to have a
> supercell twice as large as the unit cell.
>
> My cell parameters are:
> ?a=4.2949 Angstrom
> ? b=4.0316 Angstrom
> ?c=5.1650 Angstrom
> ??= 89.744 degrees
> And the other two angles, instead of being 90, are 89.947, 88.396.
>
> I appreciate any comments or suggestions.
>
>
>
> Best regards;
>
>
> Mona Asadi Namin
>
> Graduate student
>
> Center for simulational physics
>
> University of Georgia
>
> --------------------------------------
>
> Email:mona.a at uga.ed <mona.a at uga.edu>u <mona.a at uga.edu>
>
> Phone: +1-215-906-23-92
>
>
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--
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Yue-Wen FANG, PhD
Tokyo Institute of Technology, Japan
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