[QE-users] SrTiO3 Structure not converged

Fri Jun 18 09:18:04 CEST 2021

Dear Sidra

If you want to optimize the lattice constant of cubic SrtiO3 it would be 
better to do it for the simple 5 atom cubic cell, using a 2X2X2 
supercell and constraining the system to remain cubic (cell_dofree = 
'ibrav') may cause troubles.

best wishes Pietro

Il 6/18/2021 8:58 AM, Sidrah Younus Khan ha scritto:
> Dear QE users,
>
> I have 3 questions.As i have just started the calculations so i have a 
> lot of questions
> 1)I am using v-c relax calculations for my system of strontium 
> titanate. I am using 16 processors on my personal computer PC, but the 
> system does not converge even after 12 hours. I am unable to detect 
> the problem in the input & output file as some errors are coming. I 
> tried to change potentials and also the mixing -beta from 0.6-0.7.
> 2) Secondly, I need a pseudopotential 
> -Ti.pbesol-spn-rrkjus_psl.1.0.0.upf , if somebody could lead me to 
> that. as i am unable to find it
> 3) Is there any way to check the band and spin orbit coupling 
> change with temperature , as far as I know the band structure 
> calculations are working on 0K, i need to check the temperature 
> variation effect on band structure and spin orbit coupling.
>
> I am attaching my input file and some errors of output.
> &CONTROL
> calculation         = 'vc-relax',
> restart_mode        = 'from_scratch',
> wf_collect          = .true.,
> nstep               = 500
> pseudo_dir          = " . "
> prefix              = 'srTio3relax'
> outdir              = './tmp'
> etot_conv_thr       = 1.0d-6
> forc_conv_thr       = 1.0d-3
> verbosity           = 'high'
> /
>
> &SYSTEM
> ibrav               = 1,
> celldm(1)           = 14.78052,
> nat                 = 40,
> ntyp                = 3,
> ecutwfc             = 40.D0,
> ecutrho             = 320.D0,
> occupations         = 'smearing',
> smearing            = 'gauss',
> degauss             = 0.01
> /
>
> &ELECTRONS
>     diagonalization     = 'david',
>     conv_thr         =  1.0d-10
>     mixing_beta      =  0.6
> /
> &ions
> /
> &cell
>     cell_dofree='ibrav'
> /
> K_POINTS {automatic}
> 4  4  4  0 0 0
>
> ATOMIC_SPECIES
> Sr     87.62000  Sr.pbe-spn-rrkjus_psl.1.0.0.UPF
> Ti     47.86700  Tl.pbe-dn-rrkjus_psl.1.0.0.UPF
> O      15.99940  O.pbe-n-rrkjus_psl.1.0.0.UPF
>
> ATOMIC_POSITIONS {angstrom}
> Sr      0.000000   0.000000   0.000000
> Sr      0.000000   0.000000   3.945130
> Sr      0.000000   3.945130   0.000000
> Sr      0.000000   3.945130   3.945130
> Sr      3.945130   0.000000   0.000000
> Sr      3.945130   0.000000   3.945130
> Sr      3.945130   3.945130   0.000000
> Sr      3.945130   3.945130   3.945130
> Ti      1.972565   1.972565   1.972565
> Ti      1.972565   1.972565   5.917695
> Ti      1.972565   5.917695   1.972565
> Ti      1.972565   5.917695   5.917695
> Ti      5.917695   1.972565   1.972565
> Ti      5.917695   1.972565   5.917695
> Ti      5.917695   5.917695   1.972565
> Ti      5.917695   5.917695   5.917695
> O       1.972565   0.000000   1.972565
> O       1.972565   0.000000   5.917695
> O       1.972565   3.945130   1.972565
> O       1.972565   3.945130   5.917695
> O       5.917695   0.000000   1.972565
> O       5.917695   0.000000   5.917695
> O       5.917695   3.945130   1.972565
> O       5.917695   3.945130   5.917695
> O       1.972565   1.972565   0.000000
> O       1.972565   1.972565   3.945130
> O       1.972565   5.917695   0.000000
> O       1.972565   5.917695   3.945130
> O       5.917695   1.972565   0.000000
> O       5.917695   1.972565   3.945130
> O       5.917695   5.917695   0.000000
> O       5.917695   5.917695   3.945130
> O       0.000000   1.972565   1.972565
> O       0.000000   1.972565   5.917695
> O       0.000000   5.917695   1.972565
> O       0.000000   5.917695   5.917695
> O       3.945130   1.972565   1.972565
> O       3.945130   1.972565   5.917695
> O       3.945130   5.917695   1.972565
> O       3.945130   5.917695   5.917695
>
>
> _Output errors:_
> _
> _
> _1)_CASE: enthalpy_new < enthalpy_old
> 2) Check: negative core charge=   -0.000006
> _3)_WARNING: bfgs curvature condition failed, Theta= 0.977
> 4) Total force =     0.364085     Total SCF correction =   0.000016
> 5)
>  Parallelization info
>      --------------------
>      sticks:   dense  smooth     PW     G-vecs:    dense smooth      PW
>      Min         395     197     54                23717 8376    1222
>      Max         397     199     55                23719 8381    1227
>      Sum        6333    3157    877               379485 134059   19597
>
> http://www.quantum-espresso.org/quote 
> <http://www.quantum-espresso.org/quote>
>
>      Parallel version (MPI), running on    16 processors
>
>      MPI processes distributed on     1 nodes
>      R & G space division:  proc/nbgrp/npool/nimage =  16
>      Reading input from sr.vc_relax.in <http://sr.vc_relax.in>
>
>      Current dimensions of program PWSCF are:
>      Max number of different atomic species (ntypx) = 10
>      Max number of k-points (npk) =  40000
>      Max angular momentum in pseudopotentials (lmaxx) =  3
>                file Tl.pbe-dn-rrkjus_psl.1.0.0.UPF: wavefunction(s) 
>  6S 5D renormalized
>
>      Subspace diagonalization in iterative solution of the eigenvalue 
> problem:
>      one sub-group per band group will be used
>      ELPA distributed-memory algorithm (size of sub-group:  2*  2 procs)
>
> _
> _
> _
> _
> _Thanks_
> _Best Regards_
> _Sidra Younus_
> _American university of Sharjah-UAE_
> _
> _
> _
> _
> _
> _
>
>
>
> _______________________________________________
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