Dear all,
I ran a band structure calculation for the planar graphene-like SiC.
Using the following input, I got a direct gap of 2.16 eV at K symmetry point.
Now there is a question for me.
The literature generally report a direct gap of ~2.55 eV at K symmetry point.
I also tried ELK code (based on FP-LAPW method) and CASTEP code (based on norm
conserving PBE pseudopotentials)
and, as expected, got a direct gap of ~2.55 eV at K symmetry point.
Note that, the following input is only for quick test.
I have calculated the whole band structure along the G-K-M-G path with 150
k-points,
and gotten a direct gap of 2.16 eV at K symmetry point.
I have changed some parameters such as 'ecutwfc' and *.UPF, and no change was
observed.
Any suggestions?
Best regards
Youzhao Lan
***************************
&control
calculation='scf'
prefix='SiC111'
/
&system
ibrav=0,nat=2,ntyp=2
ecutwfc = 80.0
nbnd=8
/
&electrons
/
ATOMIC_SPECIES
Si 28.06 Si.pbe-mt_fhi.UPF
C 12.01 C.pbe-mt_fhi.UPF
CELL_PARAMETERS (bohr)
5.07289346 -2.92883646 0.00000000
0.00000000 5.85767273 0.00000000
0.00000000 0.00000000 37.80921171
ATOMIC_POSITIONS (crystal)
C 0.000000 0.000000 0.500000
Si 0.333333 -0.333333 0.500000
K_POINTS (crystal)
3
0.000 0.000 0.000 1.0
0.333 0.333 0.000 1.0
0.500 0.000 0.000 1.0
**************************************
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