[Pw_forum] Band Offsets too large
Dae Kwang Jun
jdaekwang at gmail.com
Wed Jun 29 07:25:16 CEST 2016
Dear all,
I tried to calculate the band offset for GaAs-AlAs. However, the valence
band offsets that I am getting are too large. I used 6 unit cells of GaAs
and 6 unit cells of AlAs stacked in the 001 direction. For the offset I
used the potential line up method. I used pw.x pp.x average.x to find the
potential line up, and I used pw.x bands.x plotband.x to find the valence
band maxima. Most literature agrees that the VBO should be around 0.44 eV
to 0.50 eV. However, I am getting 2.49 eV, which is too large. What could
be causing this?
Sincerely,
Dae Kwang Jun
Here is one of the input files that I used for the GaAs-AlAs interface
&CONTROL
calculation = 'scf'
verbosity = 'high'
restart_mode = 'from_scratch'
tstress = .true.
tprnfor = .true.
outdir = '/home/files'
prefix = '001_5x5_GaAs-AlAs'
pseudo_dir = '/home/espresso-5.4.0/pseudo'
/
&SYSTEM
ibrav = 6
a = 5.65
c = 67.8
nat = 96
ntyp = 3
ecutwfc = 70.0
occupations = 'smearing'
degauss = 0.01
/
&ELECTRONS
mixing_beta = 0.4
diagonalization = 'david'
/
ATOMIC_SPECIES
Ga 69.723 Ga.pw-mt_fhi.UPF
Al 26.981 Al.pw-mt_fhi.UPF
As 74.921 As.pw-mt_fhi.UPF
ATOMIC_POSITIONS {angstrom}
Ga 0.000000 0.000000 0.000000
Ga 0.000000 2.825000 2.825000
Ga 2.825000 0.000000 2.825000
Ga 2.825000 2.825000 0.000000
As 1.412500 1.412500 1.412500
As 4.237500 4.237500 1.412500
As 4.237500 1.412500 4.237500
As 1.412500 4.237500 4.237500
Al 0.000000 0.000000 33.900002
Al 0.000000 2.825000 36.725002
Al 2.825000 0.000000 36.725002
Al 2.825000 2.825000 33.900002
As 1.412500 1.412500 35.312500
As 4.237500 4.237500 35.312500
As 4.237500 1.412500 38.137501
As 1.412500 4.237500 38.137501
Ga 0.000000 0.000000 5.650000
Ga 0.000000 2.825000 8.475000
Ga 2.825000 0.000000 8.475000
Ga 2.825000 2.825000 5.650000
As 1.412500 1.412500 7.062500
As 4.237500 4.237500 7.062500
As 4.237500 1.412500 9.887501
As 1.412500 4.237500 9.887501
Ga 0.000000 0.000000 11.300000
Ga 0.000000 2.825000 14.125000
Ga 2.825000 0.000000 14.125000
Ga 2.825000 2.825000 11.300000
As 1.412500 1.412500 12.712501
As 4.237500 4.237500 12.712501
As 4.237500 1.412500 15.537500
As 1.412500 4.237500 15.537500
Ga 0.000000 0.000000 16.950001
Ga 0.000000 2.825000 19.775002
Ga 2.825000 0.000000 19.775002
Ga 2.825000 2.825000 16.950001
As 1.412500 1.412500 18.362501
As 4.237500 4.237500 18.362501
As 4.237500 1.412500 21.187500
As 1.412500 4.237500 21.187500
Ga 0.000000 0.000000 22.600000
Ga 0.000000 2.825000 25.425001
Ga 2.825000 0.000000 25.425001
Ga 2.825000 2.825000 22.600000
As 1.412500 1.412500 24.012501
As 4.237500 4.237500 24.012501
As 4.237500 1.412500 26.837502
As 1.412500 4.237500 26.837502
Ga 0.000000 0.000000 28.250000
Ga 0.000000 2.825000 31.075001
Ga 2.825000 0.000000 31.075001
Ga 2.825000 2.825000 28.250000
As 1.412500 1.412500 29.662500
As 4.237500 4.237500 29.662500
As 4.237500 1.412500 32.487499
As 1.412500 4.237500 32.487499
Al 0.000000 0.000000 39.549999
Al 0.000000 2.825000 42.375000
Al 2.825000 0.000000 42.375000
Al 2.825000 2.825000 39.549999
As 1.412500 1.412500 40.962498
As 4.237500 4.237500 40.962498
As 4.237500 1.412500 43.787498
As 1.412500 4.237500 43.787498
Al 0.000000 0.000000 45.200001
Al 0.000000 2.825000 48.025002
Al 2.825000 0.000000 48.025002
Al 2.825000 2.825000 45.200001
As 1.412500 1.412500 46.612499
As 4.237500 4.237500 46.612499
As 4.237500 1.412500 49.437500
As 1.412500 4.237500 49.437500
Al 0.000000 0.000000 50.850002
Al 0.000000 2.825000 53.675003
Al 2.825000 0.000000 53.675003
Al 2.825000 2.825000 50.850002
As 1.412500 1.412500 52.262501
As 4.237500 4.237500 52.262501
As 4.237500 1.412500 55.087502
As 1.412500 4.237500 55.087502
Al 0.000000 0.000000 56.500000
Al 0.000000 2.825000 59.325001
Al 2.825000 0.000000 59.325001
Al 2.825000 2.825000 56.500000
As 1.412500 1.412500 57.912498
As 4.237500 4.237500 57.912498
As 4.237500 1.412500 60.737499
As 1.412500 4.237500 60.737499
Al 0.000000 0.000000 62.150002
Al 0.000000 2.825000 64.974998
Al 2.825000 0.000000 64.974998
Al 2.825000 2.825000 62.150002
As 1.412500 1.412500 63.562500
As 4.237500 4.237500 63.562500
As 4.237500 1.412500 66.387505
As 1.412500 4.237500 66.387505
K_POINTS {automatic}
8 8 2 0 0 0
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