[QE-users] Fwd: Unable to converge scf calculation of Mn doped CsPbBr3 with spin orbit coupling included

[Debdipto Acharya]

---------- Forwarded message ----------
From: Debdipto Acharya <debdipto.acharya at gmail.com>
Date: Fri, May 4, 2018 at 4:10 PM
Subject: Unable to converge scf calculation of Mn doped CsPbBr3 with spin
orbit coupling included
To: users-request at lists.quantum-espresso.org


Dear QE users and developers,

I am currently doing a scf of Mn doped CsPbBr3 cubic perovskite with spin
orbit couping included. First, I have done the calculation of Mn doped
CsPbBr3 without spin orbit interaction (system is spin polarized). The
calculation converged without any problem. Next, I want to see the
spin-orbit effect on the system. Only Pb have significant spin-orbit
contribution. So, I have used relativistic pseudopotential for Pb atoms
only. But the calculation was not converged. The difference in energy
between two successive iteration keeps oscillating  in third decimal place.
First I have tried to reduce mixing beta upto 0.1. Then I have increased
the value of degauss. Increasing the degauss value beyond 0.02 Ry gives
problems in computing cholesky. Keeping the value of degauss at 0.02 Ry, I
have tried to increase no of bands. I have also tried to increase the
kinetic energy cutoff and do a contrained magnetization with changing the
value of lambda. I have also tried with davidson and conjugate-gradient
 diagonalization technique. But none of this helps to converge the scf
calculation. I am attaching the input file and output file

************************************************************
*******************************
  &control
    calculation = 'scf'
    restart_mode='from_scratch',
    prefix='Mn-CsPbBr3-cubic',
    tstress = .true.
    tprnfor = .true.
    verbosity = 'high'
    pseudo_dir = './pseudo/',
    outdir='./tmp'
    max_seconds = 82800
 /
 &system
    ibrav=  1,
    celldm(1) = 22.6992,
    nat=  40, ntyp= 4,
    ecutwfc = 40,
    ecutrho = 400,
    occupations = 'smearing' ,
    nbnd = 1200
    starting_magnetization(1)=1
    degauss = 0.02 ,
    smearing = 'm-v'
    noncolin = .true.,
    lspinorb = .true.
 /
 &electrons
    electron_maxstep = 400
    diagonalization='david'
    mixing_mode = 'local-TF'
    mixing_beta = 0.1
    conv_thr =  1.0d-6
 /
ATOMIC_SPECIES
Mn  54.938 Mn.pbe-spn-rrkjus_psl.0.3.1.UPF
Cs 132.91  Cs.pbe-spn-rrkjus_psl.0.2.3.UPF
Pb 207.20  Pb.rel-pbe-dn-rrkjus_psl.0.2.2.UPF
Br  79.904 Br.pbe-n-rrkjus_psl.0.2.UPF
ATOMIC_POSITIONS {alat}
Cs       0.007178446   0.007178446   0.007178446
Cs       0.007178446   0.007178446   0.492821554
Cs       0.007178446   0.492821554   0.007178446
Cs       0.007178446   0.492821554   0.492821554
Cs       0.492821554   0.007178446   0.007178446
Cs       0.492821554   0.007178446   0.492821554
Cs       0.492821554   0.492821554   0.007178446
Cs       0.492821554   0.492821554   0.492821554
Br       0.017759934   0.250000000   0.250000000
Br       0.250000000   0.017759934   0.250000000
Br       0.250000000   0.250000000   0.017759934
Br       0.001381219   0.250000000   0.750000000
Br       0.250000000   0.001381219   0.750000000
Br       0.250000000   0.250000000   0.482240066
Br       0.001381219   0.750000000   0.250000000
Br       0.250000000   0.482240066   0.250000000
Br       0.250000000   0.750000000   0.001381219
Br       0.000903279   0.750000000   0.750000000
Br       0.250000000   0.498618781   0.750000000
Br       0.250000000   0.750000000   0.498618781
Br       0.482240066   0.250000000   0.250000000
Br       0.750000000   0.001381219   0.250000000
Br       0.750000000   0.250000000   0.001381219
Br       0.498618781   0.250000000   0.750000000
Br       0.750000000   0.000903279   0.750000000
Br       0.750000000   0.250000000   0.498618781
Br       0.498618781   0.750000000   0.250000000
Br       0.750000000   0.498618781   0.250000000
Br       0.750000000   0.750000000   0.000903279
Br       0.499096721   0.750000000   0.750000000
Br       0.750000000   0.499096721   0.750000000
Br       0.750000000   0.750000000   0.499096721
Mn       0.250000000   0.250000000   0.250000000
Pb       0.250000000   0.250000000   0.750000000
Pb       0.250000000   0.750000000   0.250000000
Pb       0.250000000   0.750000000   0.750000000
Pb       0.750000000   0.250000000   0.250000000
Pb       0.750000000   0.250000000   0.750000000
Pb       0.750000000   0.750000000   0.250000000
Pb       0.750000000   0.750000000   0.750000000
K_POINTS {automatic}
4  4  4  0  0  0

************************************************************
******************
 I would really appreciate any suggestion. Thanks in advance

Regards

Debdipto Acharya

Ph.D student,

Prof. Shobhana Narasimhan's Lab,

JNCASR, Bangalore, India
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