[QE-users] Medium-entropy materials

[Lorenzo Paulatto]

Are you sure that the atoms positions are correct? Very close atoms can 
cause convergence problems. I would check with xcrysden, or the 
online-tool seekpath, or with dist.x


cheers


On 18/07/2022 15:45, Connor Wilson wrote:
> Hi everyone,
>
> I am trying to obtain a converged SCF calculation (using Quantum 
> ESPRESSO, version 7.0) for the medium-entropy oxide (CoCuMgZn)_0.25 
>  O. This material crystalizes in the rocksalt structure. I am using a 
> 64-atom supercell. I have attached my input file at the end of this 
> message.
>
> My problem is: after 50 iterations, my calculations show no trend 
> towards convergence (ie. the 'estimated scf accuracies' in the pw.x 
> output file stabilize around 0.5 Ry). I have made the following 
> adjustments in an effort to achieve better convergence:
>
>   * using degauss values of 0.001, 0.01, 0.02
>   * using a 6 x 6 x 6 K-mesh
>   * using mixing_beta of 0.05, 0.1, 0.2
>   * using ecutwfc of 60, 70, 100 (each with 10x ecutrho)
>   * using PBEsol, PBE pseudopotentials
>
> My question is: do you think it is possible to achieve a converged SCF 
> calculation using QE? If it is, what might an appropriate value of 
> conv_thr be, and could you suggest other changes to my input file I 
> could try?
>
> Thank you for your time,
>
>
> Connor Wilson
> Brock University
> Department of Mathematics and Science
> 1812 Sir Issac Brock Way, St. Catharines, ON, CAN, L2S 3A1
>
>
>
>
>
>
> ######################## pw.x input ###########################
>
> &CONTROL
>   calculation = 'scf',
>   prefix = 'MEO',
>   tstress = .true.,
>   tprnfor = .true.,
>   restart_mode = 'from_scratch',
>   outdir = '/home/cw279/projects/def-crandles/cw279/MEO/222c/alat'
>   pseudo_dir = '/home/cw279/pseudo',
> /
>
> &SYSTEM
>   ibrav = 1,
>   celldm(1) = 15.1,
>   nat = 64,
>   ntyp = 5,
>   ecutwfc = 100,
>   ecutrho = 1000,
>   occupations = 'smearing',
>   smearing = 'mv',
>   degauss = 0.01,
> /
>
> &ELECTRONS
>   electron_maxstep = 50,
>   mixing_beta = 0.1,
>   conv_thr  = 1.0d-6,
>   mixing_mode = 'local-TF',
>   mixing_ndim = 10,
> /
>
> ATOMIC_SPECIES
>   Mg  24.305   Mg.pbe-spnl-kjpaw_psl.1.0.0.UPF
>   O   15.9994  O.pbe-n-kjpaw_psl.1.0.0.UPF
>   Zn  65.380   Zn.pbe-dnl-kjpaw_psl.1.0.0.UPF
>   Ni  58.6934  Ni.pbe-spn-kjpaw_psl.1.0.0.UPF
>   Co  58.9332  Co.pbe-spn-kjpaw_psl.0.3.1.UPF
>
> K_POINTS {automatic}
>   4 4 4  0 0 0
>
> ATOMIC_POSITIONS {crystal}
> ........
>
>
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-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC - CNRS UMR 7590 & Sorbonne Université
phone: +33 (0)1 442 79822 / skype: paulatz
http://www.impmc.upmc.fr/~paulatto/ - https://anharmonic.github.io/
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