[QE-users] CuO relaxation problem

[Yue-Wen Fang]

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> 于2020年7月13日周一 下午10:15写道：

> 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
> •β= 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
>
>
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users



-- 
------------------------------------------------------------------------------------------------------------
Yue-Wen FANG, PhD
Tokyo Institute of Technology, Japan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20200713/889af0ea/attachment.html>