[QE-users] convergence NOT achieved

[mehrdad zamzamian]

With regards
Maybe my question is very repetitive but i could found nothing in the forum
to help. I am trying to run a vc-relax for cementite structure using
GGA-USPP. The problem is that i cannot achieve any convergence even after
1000 iteration. The total energy fluctuates in the order of ~0.1! By using
other PP, i simply achieved to the convergence, but i need to use these pp
ones. I would appreciate any suggestions in this regard.
This is my input:
&CONTROL
    calculation   = "vc-relax"
    forc_conv_thr =  1.00000e-03
    max_seconds   =  8.64000e+07
    nstep         = 1000
    pseudo_dir    = "..../bin"
/

&SYSTEM
    a                         =  5.03018e+00
    angle1(1)                 =  0.00000e+00
    angle2(1)                 =  0.00000e+00
    b                         =  6.73931e+00
    c                         =  4.49084e+00
    degauss                   =  1.00000e-02
    ecutrho                   =  6.37306e+02
    ecutwfc                   =  7.08118e+01
    ibrav                     = 8
    lda_plus_u                = .FALSE.
    nat                       = 16
    nspin                     = 2
    ntyp                      = 2
    occupations               = "smearing"
    smearing                  = "gaussian"
    starting_magnetization(1) =  4.00000e-01
    starting_magnetization(2) =  0.00000e+00
/

&ELECTRONS
    conv_thr         =  1.00000e-06
    electron_maxstep = 2000
    mixing_beta      =  4.00000e-01
    startingpot      = "atomic"
    startingwfc      = "atomic+random"
/

&IONS
    ion_dynamics = "bfgs"
/

&CELL
    cell_dofree    = "xyz"
    cell_dynamics  = "bfgs"
    press          =  0.00000e+00
    press_conv_thr =  5.00000e-01
/

K_POINTS {automatic}
 2  2  3  0 0 0

ATOMIC_SPECIES
Fe     55.84500  Fe.pbe-spn-rrkjus_psl.1.0.0.UPF
C      12.01070  C.pbe-n-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS {angstrom}
Fe      0.892203   0.460793   1.491414
Fe      4.137977   6.278514   2.999431
Fe      1.622887   6.278514   3.736836
Fe      3.407293   0.460793   0.754008
Fe      3.407293   2.908860   0.754008
Fe      1.622887   3.830447   3.736836
Fe      4.137977   3.830447   2.999431
Fe      0.892203   2.908860   1.491414
Fe      0.184411   1.684827   3.759376
Fe      4.845769   5.054480   0.731469
Fe      2.330679   5.054480   1.513954
Fe      2.699502   1.684827   2.976891
C       0.618742   5.054480   2.519058
C       4.411438   1.684827   1.971786
C       1.896348   1.684827   0.273636
C       3.133833   5.054480   4.217209

Thanks

Seyed Mehrdad Zamzamian
Sharif University of Technology, Tehran, Iran
Energy engineering department
E-mail: mehrdad.zamzamian at gmail.com
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