[QE-users] oscillating energy value during optimization

[Coralie Khabbaz]

Hello,

My structure is a WN slab with molecules adsorbing on its surface. I always
have problems with convergence: everytime I try to relax the structure,
multiple scf steps converge, but then the energy value starts oscillating
and it doesn't converge anymore. My structure gets stuck every time, even
though I visualized it after every scf step and the structure seems fine.
This is the input file I am using. I also tried decreasing the degauss to
1e-2, increasing ecutrho and ecutwfc by a little bit, decreasing
mixing_beta to 6e-2 and also tried changing the mixing_mode to TF, but
nothing worked! Does anyone have advice? Thank you!

&CONTROL
    calculation   = "relax"
    forc_conv_thr =  1.00000e-03
    max_seconds   =  4.32000e+05
    nstep         = 200
    pseudo_dir    = "/home/coralee/projects/def-jkopysci/coralee/.pseudopot"
/

&SYSTEM
    a                         =  8.32716e+00
    angle1(1)                 =  0.00000e+00
    angle2(1)                 =  0.00000e+00
    b                         =  8.98689e+00
    c                         =  2.52767e+01
    cosab                     =  6.12323e-17
    cosac                     =  6.12323e-17
    cosbc                     = -1.85547e-01
    degauss                   =  2.00000e-02
    ecutrho                   =  4.75221e+02
    ecutwfc                   =  5.03902e+01
    ibrav                     = 12
    nat                       = 53
    nbnd                      = 480
    nspin                     = 2
    ntyp                      = 4
    occupations               = "smearing"
    smearing                  = "gaussian"
    starting_magnetization(1) =  2.00000e-01
    starting_magnetization(2) =  2.00000e-01
    starting_magnetization(3) =  0.00000e+00
    starting_magnetization(4) =  0.00000e+00
/

&ELECTRONS
    conv_thr         =  1.00000e-05
    diagonalization  = "david"
    electron_maxstep = 200
    mixing_beta      =  1.00000e-01
    mixing_mode      = "local-TF"
    startingpot      = "atomic"
    startingwfc      = "atomic+random"
/

&IONS
    ion_dynamics = "bfgs"
/

&CELL
/

K_POINTS {automatic}
 2  2  1  0 0 0

ATOMIC_SPECIES
N      14.00674  N.pbe-n-kjpaw_psl.1.0.0.UPF
W     183.84000  W.pbe-spn-kjpaw_psl.1.0.0.UPF
C      12.01070  C.pbe-n-kjpaw_psl.1.0.0.UPF
H       1.00794  H.pbe-kjpaw_psl.1.0.0.UPF

ATOMIC_POSITIONS {angstrom}
N       3.210864   2.727236  14.728253
N       7.377521   2.749437  14.765113
N       3.206885  -1.748226  14.750672
N       7.368425  -1.739825  14.763088
W       3.182078   4.921673  14.584931
W       7.371236   4.911599  14.572299
W       3.210468   0.427880  14.572328
W       7.375435   0.429218  14.573322
N       1.114319   5.237998  14.590842
N       5.297509   5.253239  14.643339
N       1.127456   0.739579  14.633097
N       5.291670   0.741857  14.637218
W       1.130917   3.035176  14.411937
W       5.301873   3.012738  14.402683
W       1.122976  -1.443293  14.413944
W       5.288433  -1.443790  14.404037
N       3.219452   5.199606  12.448287
N       7.366466   5.188650  12.437657
N       3.207970   0.704887  12.465361
N       7.371281   0.697722  12.461527
W       3.205392   3.068813  12.535650
W       7.371059   3.075963  12.535225
W       3.208342  -1.417371  12.526978
W       7.371423  -1.415702  12.526259
N       1.126718   3.566876  12.355498
N       5.287387   3.570864  12.349260
N       1.127573  -0.926625  12.347835
N       5.290289  -0.925589  12.354591
W       1.124934   5.676097  12.168934
W       5.300233   5.687505  12.124192
W       1.125212   1.183514  12.166731
W       5.291832   1.185520  12.166744
N       3.207882   3.506729  10.422372  0 0 0
N       7.371462   3.506729  10.422372  0 0 0
N       3.207882  -0.986715  10.422372  0 0 0
N       7.371462  -0.986715  10.422372  0 0 0
W       3.207882   5.716584  10.333236  0 0 0
W       7.371462   5.716584  10.333236  0 0 0
W       3.207882   1.223140  10.333236  0 0 0
W       7.371462   1.223140  10.333236  0 0 0
N       1.126093   6.199382  10.052766  0 0 0
N       5.289672   6.199382  10.052766  0 0 0
N       1.126093   1.705938  10.052766  0 0 0
N       5.289672   1.705938  10.052766  0 0 0
W       1.126093   3.871912  10.000000  0 0 0
W       5.289672   3.871912  10.000000  0 0 0
W       1.126093  -0.621532  10.000000  0 0 0
W       5.289672  -0.621532  10.000000  0 0 0
C       4.904436   5.088998  16.341705
H       4.817236   4.340738  17.152672
H       4.810563   5.831388  17.155825
H       3.209512   2.314472  17.745318
H       3.207503   3.080782  17.746006
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