[QE-users] Issue with Nanoribbon Band Structure of GeI

[Tamas Karpati]

Dear Larry,

You have almost 300 electrons which means ca. 150 occupied bands,
while you forced QE to use just 2^7. Funny that SCF converged, proves
stability of PWscf :)

Try to increase nbnd above 150.

Hope this helps,
  t


On Wed, Aug 5, 2020 at 3:55 AM Larry Shi <larryshi02 at gmail.com> wrote:

> Dear QE gurus,
>
> I am new to QE and I am currently trying to replicate the band structure
> for a GeI nanoribbon (https://doi.org/10.1103/PhysRevB.89.115429). I
> passivated the Ge atoms with H atoms. When I run the band input file
> (below) after the SCF has been converged, the bands in the resulting band
> structure are all straight lines (they all have constant energy), which is
> absurd. I'm not sure where the issue originates.
>
> Any assistance would be greatly appreciated!
>
>
> &CONTROL
>     calculation = "bands"
>     max_seconds =  5.18400e+06
>     pseudo_dir  = "C:\Users\User\.burai\.pseudopot"
> /
>
> &SYSTEM
>     a                         =  4.62000e+01
>     angle1(1)                 =  0.00000e+00
>     angle1(2)                 =  0.00000e+00
>     angle2(1)                 =  0.00000e+00
>     angle2(2)                 =  0.00000e+00
>     b                         =  7.01480e+00
>     c                         =  3.00000e+01
>     cosab                     = -5.00000e-01
>     degauss                   =  1.00000e-02
>     ecutrho                   =  1.00000e+02
>     ecutwfc                   =  2.50000e+01
>     ibrav                     = 8
>     lspinorb                  = .FALSE.
>     nat                       = 32
>     nbnd                      = 128
>     nspin                     = 1
>     ntyp                      = 3
>     occupations               = "smearing"
>     smearing                  = "gaussian"
>     starting_magnetization(1) =  0.00000e+00
>     starting_magnetization(2) =  0.00000e+00
> /
>
> &ELECTRONS
>     conv_thr         =  1.00000e-07
>     electron_maxstep = 200
>     mixing_beta      =  7.00000e-01
>     startingpot      = "atomic"
>     startingwfc      = "atomic+random"
> /
>
> &BANDS
>     lsym           = .FALSE.
>     spin_component = 1
> /
>
> K_POINTS {tpiba_b}
> 3
> Z      40
> gG     40
> Z      40
>
> ATOMIC_SPECIES
> Ge     72.61000  Ge.pbe-n-rrkjus_psl.1.0.0.UPF
> I     126.90447  I.pbe-mt_bw.UPF
> H       1.00794  H.pbe-rrkjus.UPF
>
> ATOMIC_POSITIONS {angstrom}
> H      -2.005606   1.098069  29.911525
> Ge      0.019394   2.178887   0.673171
> Ge      1.988303   1.098069  29.911525
> I       0.170697   2.062988   3.223532
> I       2.089141   1.028047  27.356392
> H      -2.005606   5.686290   0.673171
> Ge     -0.036697   4.605472  29.911525
> I       0.064141   4.535450  27.356392
> Ge      4.069394   2.178887   0.673171
> Ge      6.038303   1.098069  29.911525
> I       4.220697   2.062988   3.223532
> I       6.139141   1.028047  27.356392
> Ge      2.044394   5.686290   0.673171
> Ge      4.013303   4.605472  29.911525
> I       2.195697   5.570391   3.223532
> I       4.114141   4.535450  27.356392
> Ge      8.119394   2.178887   0.673171
> Ge     10.088303   1.098069  29.911525
> I       8.270697   2.062988   3.223532
> I      10.189141   1.028047  27.356392
> Ge      6.094394   5.686290   0.673171
> Ge      8.063303   4.605472  29.911525
> I       6.245697   5.570391   3.223532
> I       8.164141   4.535450  27.356392
> Ge     12.169394   2.178887   0.673171
> H      14.138303   1.098069  29.911525
> I      12.320697   2.062988   3.223532
> Ge     10.144394   5.686290   0.673171
> Ge     12.113303   4.605472  29.911525
> I      10.295697   5.570391   3.223532
> I      12.214141   4.535450  27.356392
> H      14.138303   5.686290   0.673171
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