8
$\begingroup$

Currently, I am working on ZnO doped with nickel and cobalt.

I performed the SCF, NCF, BANDS calculation and got the results, the calculation converges without any errors.

After that I used BANDS.X to get the structures of the bands (broken lines) shown below. but the lines of the valence band look unusual. I do not understand why, do i have to change something in the input files to have regular lines in the bands structure

enter image description here

I would be grateful if anyone could help me figure out how to solve this problem

Input files:

&CONTROL
    calculation='scf'
    verbosity='high'
    outdir  ='./outdir0'
    prefix  = 'zno'
/
&SYSTEM

    celldm(1)                 =  21.40319287
    celldm(3)                 =  0.42031128
    degauss                   =  1.00000e-02
    ecutrho                   =  2.25000e+02
    ecutwfc                   =  2.50000e+01
    hubbard_u(1)              =  1.00000e+01
    hubbard_u(2)              =  7.00000e+00
    hubbard_u(3)              =  3.30000e+00
    hubbard_u(4)              =  6.40000e+00
    ibrav                     = 4
    lda_plus_u                = .TRUE.
    nat                       = 64
    nspin                     = 2
    ntyp                      = 4
    occupations               = "smearing"
    smearing                  = "gaussian"
    starting_magnetization(1) =  0.00000e+00
    starting_magnetization(2) =  0.00000e+00
    starting_magnetization(3) =  1.00000e+00
    starting_magnetization(4) =  1.00000e+00
/

&ELECTRONS
    conv_thr         =  1.00000e-06
    electron_maxstep = 1000
    mixing_beta      =  7.00000e-01
    startingpot      = "atomic"
    startingwfc      = "atomic+random"
/

K_POINTS {automatic}
 1  1  2  0 0 0

ATOMIC_SPECIES
Zn     65.39000  Zn.pbe-dnl-rrkjus_psl.1.0.0.UPF
O      15.99940  O.pbe-n-rrkjus_psl.1.0.0.UPF
Co     58.93320  Co.pbe-spn-rrkjus_psl.0.3.1.UPF
Ni     58.69340  Ni.pbe-spn-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS {angstrom}
Zn       1.410161044   0.825995833   2.380992801
Zn      -0.005429322   1.643266003   0.000756804
O        1.411103994   0.826287146   4.186635975
O       -0.004748346   1.642515898   1.806356445
Zn      -0.005516345   3.278786045   2.381245055
Zn      -1.419971282   4.097701065   0.001850277
O       -0.002798492   3.277411927   4.186681410
O       -1.420408761   4.092914533   1.803518434
Co      -1.418796177   5.737987580   2.384585461
Zn      -2.834720550   6.547227769   0.000881320
O       -1.422621217   5.728278992   4.185274022
O       -2.839808876   6.544154464   1.803705508
Zn      -2.837557287   8.183674136   2.381283724
Zn      -4.252922611   8.999365922   0.000439200
O       -2.837160076   8.183295309   4.186352705
O       -4.252778394   8.999185384   1.806247618
Zn       4.241315211   0.825532190   2.381126062
Zn       2.826326309   1.643228258   0.000953899
O        4.242086608   0.827637833   4.187714131
O        2.826296455   1.642373986   1.806396627
Zn       2.824771427   3.281480594   2.381223601
Zn       1.410630100   4.096454188   0.000348962
O        2.829294361   3.277876925   4.186011005
O        1.408295070   4.091216703   1.805811442
Zn       1.414986914   5.731953488   2.381740527
Zn      -0.003889577   6.546816914   0.001471199
O        1.407469304   5.728334147   4.188751652
O       -0.007390107   6.544762033   1.803264178
Zn      -0.003327618   8.182005863   2.381621288
Zn      -1.420174649   8.999121824   0.000605799
O       -0.005038456   8.183109394   4.186299484
O       -1.422019740   8.999623285   1.805713335
Zn       7.074368960   0.824266725   2.381038272
Zn       5.658165161   1.641466511   0.001428145
O        7.072366692   0.826925817   4.185876987
O        5.657781142   1.643195079   1.806011335
Zn       5.660936107   3.273250277   2.380793392
Zn       4.239021566   4.101799131   0.000974597
O        5.656833118   3.276218912   4.184993975
O        4.230283881   3.987942736   1.752313988
Ni       4.556125575   5.359987165   2.507242555
Zn       2.822577415   6.549618757  -0.002501852
O        4.241256251   5.729384302   4.181685069
O        2.889746313   6.512400957   1.840699848
Zn       2.831814541   8.170887246   2.382231895
Zn       1.411768031   8.997746180   0.000157807
O        2.830565389   8.180204499   4.188372520
O        1.410158759   9.000713184   1.805698039
Zn       9.904721317   0.824048816   2.380672192
Zn       8.489987876   1.641958804   0.000861323
O        9.905515013   0.828559672   4.186395649
O        8.489434493   1.643995005   1.805707065
Zn       8.491348975   3.277332149   2.381672239
Zn       7.075554658   4.094592895  -0.001192399
O        8.487517217   3.277350003   4.187187336
O        7.079637920   4.091302394   1.804853403
Zn       7.070336637   5.730421815   2.381711957
Zn       5.657529623   6.551672595   0.003357063
O        7.061570500   5.730823283   4.183934701
O        5.626730523   6.537239405   1.818160581
Zn       5.654350538   8.182766059   2.381132006
Zn       4.240971534   8.998159127   0.002754675
O        5.659147597   8.182586948   4.186976982
O        4.243691097   8.999467758   1.805287550

,

&CONTROL
    calculation='nscf'
    verbosity='high'
    outdir  ='./outdir0'
    prefix  = 'zno'
/
&SYSTEM
    celldm(1)                 =  21.40319287
    celldm(3)                 =  0.42031128
    degauss                   =  1.00000e-02
    ecutrho                   =  2.25000e+02
    ecutwfc                   =  2.50000e+01
    hubbard_u(1)              =  1.00000e+01
    hubbard_u(2)              =  7.00000e+00
    hubbard_u(3)              =  3.30000e+00
    hubbard_u(4)              =  6.40000e+00
    ibrav                     = 4
    lda_plus_u                = .TRUE.
    nat                       = 64
    nbnd                      = 416
    nspin                     = 2
    ntyp                      = 4
    occupations               = "smearing"
    smearing                  = "gaussian"
    starting_magnetization(1) =  0.00000e+00
    starting_magnetization(2) =  0.00000e+00
    starting_magnetization(3) =  1.00000e+00
    starting_magnetization(4) =  1.00000e+00
/

&ELECTRONS
    conv_thr         =  1.00000e-06
    electron_maxstep = 1000
    mixing_beta      =  7.00000e-01
    startingpot      = "atomic"
    startingwfc      = "atomic+random"
/
K_POINTS {automatic}
 2  2  5  0 0 0

ATOMIC_SPECIES
Zn     65.39000  Zn.pbe-dnl-rrkjus_psl.1.0.0.UPF
O      15.99940  O.pbe-n-rrkjus_psl.1.0.0.UPF
Co     58.93320  Co.pbe-spn-rrkjus_psl.0.3.1.UPF
Ni     58.69340  Ni.pbe-spn-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS {angstrom}
Zn       1.410161044   0.825995833   2.380992801
Zn      -0.005429322   1.643266003   0.000756804
O        1.411103994   0.826287146   4.186635975
O       -0.004748346   1.642515898   1.806356445
Zn      -0.005516345   3.278786045   2.381245055
Zn      -1.419971282   4.097701065   0.001850277
O       -0.002798492   3.277411927   4.186681410
O       -1.420408761   4.092914533   1.803518434
Co      -1.418796177   5.737987580   2.384585461
Zn      -2.834720550   6.547227769   0.000881320
O       -1.422621217   5.728278992   4.185274022
O       -2.839808876   6.544154464   1.803705508
Zn      -2.837557287   8.183674136   2.381283724
Zn      -4.252922611   8.999365922   0.000439200
O       -2.837160076   8.183295309   4.186352705
O       -4.252778394   8.999185384   1.806247618
Zn       4.241315211   0.825532190   2.381126062
Zn       2.826326309   1.643228258   0.000953899
O        4.242086608   0.827637833   4.187714131
O        2.826296455   1.642373986   1.806396627
Zn       2.824771427   3.281480594   2.381223601
Zn       1.410630100   4.096454188   0.000348962
O        2.829294361   3.277876925   4.186011005
O        1.408295070   4.091216703   1.805811442
Zn       1.414986914   5.731953488   2.381740527
Zn      -0.003889577   6.546816914   0.001471199
O        1.407469304   5.728334147   4.188751652
O       -0.007390107   6.544762033   1.803264178
Zn      -0.003327618   8.182005863   2.381621288
Zn      -1.420174649   8.999121824   0.000605799
O       -0.005038456   8.183109394   4.186299484
O       -1.422019740   8.999623285   1.805713335
Zn       7.074368960   0.824266725   2.381038272
Zn       5.658165161   1.641466511   0.001428145
O        7.072366692   0.826925817   4.185876987
O        5.657781142   1.643195079   1.806011335
Zn       5.660936107   3.273250277   2.380793392
Zn       4.239021566   4.101799131   0.000974597
O        5.656833118   3.276218912   4.184993975
O        4.230283881   3.987942736   1.752313988
Ni       4.556125575   5.359987165   2.507242555
Zn       2.822577415   6.549618757  -0.002501852
O        4.241256251   5.729384302   4.181685069
O        2.889746313   6.512400957   1.840699848
Zn       2.831814541   8.170887246   2.382231895
Zn       1.411768031   8.997746180   0.000157807
O        2.830565389   8.180204499   4.188372520
O        1.410158759   9.000713184   1.805698039
Zn       9.904721317   0.824048816   2.380672192
Zn       8.489987876   1.641958804   0.000861323
O        9.905515013   0.828559672   4.186395649
O        8.489434493   1.643995005   1.805707065
Zn       8.491348975   3.277332149   2.381672239
Zn       7.075554658   4.094592895  -0.001192399
O        8.487517217   3.277350003   4.187187336
O        7.079637920   4.091302394   1.804853403
Zn       7.070336637   5.730421815   2.381711957
Zn       5.657529623   6.551672595   0.003357063
O        7.061570500   5.730823283   4.183934701
O        5.626730523   6.537239405   1.818160581
Zn       5.654350538   8.182766059   2.381132006
Zn       4.240971534   8.998159127   0.002754675
O        5.659147597   8.182586948   4.186976982
O        4.243691097   8.999467758   1.805287550

,

    &CONTROL
    calculation='bands'
    verbosity='high'
    outdir  ='./outdir0'
    prefix  = 'zno'
/
&SYSTEM
    celldm(1)                 =  21.40319287
    celldm(3)                 =  0.42031128
    degauss                   =  1.00000e-02
    ecutrho                   =  2.25000e+02
    ecutwfc                   =  2.50000e+01
    hubbard_u(1)              =  1.00000e+01
    hubbard_u(2)              =  7.00000e+00
    hubbard_u(3)              =  3.30000e+00
    hubbard_u(4)              =  6.40000e+00
    ibrav                     = 4
    lda_plus_u                = .TRUE.
    nat                       = 64
    nbnd                      = 416
    nspin                     = 2
    ntyp                      = 4
    occupations               = "smearing"
    smearing                  = "gaussian"
    starting_magnetization(1) =  0.00000e+00
    starting_magnetization(2) =  0.00000e+00
    starting_magnetization(3) =  1.00000e+00
    starting_magnetization(4) =  1.00000e+00
/

&ELECTRONS
    conv_thr         =  1.00000e-06
    electron_maxstep = 1000
    mixing_beta      =  7.00000e-01
    startingpot      = "atomic"
    startingwfc      = "atomic+random"
/



K_POINTS {tpiba_b}
12
gG     20
M      20
K      20
gG     20
A      20
L      20
H      20
A      0
L      20
M      0
K      20
H      0

ATOMIC_SPECIES
Zn     65.39000  Zn.pbe-dnl-rrkjus_psl.1.0.0.UPF
O      15.99940  O.pbe-n-rrkjus_psl.1.0.0.UPF
Co     58.93320  Co.pbe-spn-rrkjus_psl.0.3.1.UPF
Ni     58.69340  Ni.pbe-spn-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS {angstrom}
Zn       1.410161044   0.825995833   2.380992801
Zn      -0.005429322   1.643266003   0.000756804
O        1.411103994   0.826287146   4.186635975
O       -0.004748346   1.642515898   1.806356445
Zn      -0.005516345   3.278786045   2.381245055
Zn      -1.419971282   4.097701065   0.001850277
O       -0.002798492   3.277411927   4.186681410
O       -1.420408761   4.092914533   1.803518434
Co      -1.418796177   5.737987580   2.384585461
Zn      -2.834720550   6.547227769   0.000881320
O       -1.422621217   5.728278992   4.185274022
O       -2.839808876   6.544154464   1.803705508
Zn      -2.837557287   8.183674136   2.381283724
Zn      -4.252922611   8.999365922   0.000439200
O       -2.837160076   8.183295309   4.186352705
O       -4.252778394   8.999185384   1.806247618
Zn       4.241315211   0.825532190   2.381126062
Zn       2.826326309   1.643228258   0.000953899
O        4.242086608   0.827637833   4.187714131
O        2.826296455   1.642373986   1.806396627
Zn       2.824771427   3.281480594   2.381223601
Zn       1.410630100   4.096454188   0.000348962
O        2.829294361   3.277876925   4.186011005
O        1.408295070   4.091216703   1.805811442
Zn       1.414986914   5.731953488   2.381740527
Zn      -0.003889577   6.546816914   0.001471199
O        1.407469304   5.728334147   4.188751652
O       -0.007390107   6.544762033   1.803264178
Zn      -0.003327618   8.182005863   2.381621288
Zn      -1.420174649   8.999121824   0.000605799
O       -0.005038456   8.183109394   4.186299484
O       -1.422019740   8.999623285   1.805713335
Zn       7.074368960   0.824266725   2.381038272
Zn       5.658165161   1.641466511   0.001428145
O        7.072366692   0.826925817   4.185876987
O        5.657781142   1.643195079   1.806011335
Zn       5.660936107   3.273250277   2.380793392
Zn       4.239021566   4.101799131   0.000974597
O        5.656833118   3.276218912   4.184993975
O        4.230283881   3.987942736   1.752313988
Ni       4.556125575   5.359987165   2.507242555
Zn       2.822577415   6.549618757  -0.002501852
O        4.241256251   5.729384302   4.181685069
O        2.889746313   6.512400957   1.840699848
Zn       2.831814541   8.170887246   2.382231895
Zn       1.411768031   8.997746180   0.000157807
O        2.830565389   8.180204499   4.188372520
O        1.410158759   9.000713184   1.805698039
Zn       9.904721317   0.824048816   2.380672192
Zn       8.489987876   1.641958804   0.000861323
O        9.905515013   0.828559672   4.186395649
O        8.489434493   1.643995005   1.805707065
Zn       8.491348975   3.277332149   2.381672239
Zn       7.075554658   4.094592895  -0.001192399
O        8.487517217   3.277350003   4.187187336
O        7.079637920   4.091302394   1.804853403
Zn       7.070336637   5.730421815   2.381711957
Zn       5.657529623   6.551672595   0.003357063
O        7.061570500   5.730823283   4.183934701
O        5.626730523   6.537239405   1.818160581
Zn       5.654350538   8.182766059   2.381132006
Zn       4.240971534   8.998159127   0.002754675
O        5.659147597   8.182586948   4.186976982
O        4.243691097   8.999467758   1.805287550

,

&bands
    outdir  ='./outdir0'
    prefix  = 'zno'
  filband='bandspp.Down.dat'
  
/
$\endgroup$
11
  • 4
    $\begingroup$ What part seems strange $\endgroup$ – Tristan Maxson Jan 24 at 0:11
  • 1
    $\begingroup$ You have a lot of atoms which are inequivalent, i dont see a significant issue. Compare it to undoped. $\endgroup$ – Tristan Maxson Jan 24 at 1:23
  • 1
    $\begingroup$ @ismailbenaicha as others have said, in a large defective cell you expect a lot of band folding, so you would expect many bands. Additionally, both Co and Ni have $d$ electrons that one would expect to lead to relatively flat bands, so your calculations may be correct. A good question to ask yourself is whether plotting the band structure of a defect system (without translational symmetry) is the best way to go, because after all without translational symmetry there is no Brillouin zone. $\endgroup$ – ProfM Jan 24 at 15:57
  • 1
    $\begingroup$ @ProfM The ecutwfc in OP's input file is 25 (and not 250)? 'ecutrho' is around 10 times larger than 'ecutwfc' so I'm guessing OP is using Ultrasoft PPs. And for conv_thr, I'm taking about the convergence threshold for electrons in the SCF step. The default for this is 1e-6, not 1e-4. This is a bit iffy, but I can understand this is a defect cell. Either way, the convergence test must be passed first, yes? $\endgroup$ – Xivi76 Jan 24 at 18:42
  • 2
    $\begingroup$ @Xivi76 my bad, you are right, I misread the 25 Ry, and you are also right about 'conv_thr', the default $10^{-6}$ (which they are using). And yes, I agree with you that convergence tests must first be passed. However, I still think that even with poor convergence, the bands look like what one may expect for a large defect cell. $\endgroup$ – ProfM Jan 24 at 19:15

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