[QE-users] CuO relaxation problem

[Mona Asadinamin]

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<mailto:mona.a at uga.edu>u<mailto:mona.a at uga.edu>
Phone: +1-215-906-23-92

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