QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: voves on December 11, 2009, 14:13
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Hi,
I tried different pseudopotential sets for fcc InSb crystal in ATK SE. All results show huge value of the bandgap (several eV). I appreciate any recommendation.
Jan
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There are no pseudopotential set in ATK-SE.
Are you taking about the basis set?
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I've seen similar results for GaAs. I think we need specific basis sets for the binary alloys; the current parameters are adapted for pure Ga and As (or In and Sb), not the alloy. This is how semi-empirical methods work - the results are only as good as the parameters.
If anyone knows of extended Huckel basis sets for the III-V alloys, we'll be very interested in testing them!
We can also try to fit our own set, but it's a bit of a task...
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I should correct my own statement a bit. There are already GaAs parameters from Cerda in ATK now, and also AlP, InAs, and some other III-V binaries. However, exactly InSb is missing...
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Could be possible to include parameters for InSb from:
Yajun Wei and Manijeh Razeghi
Modeling of type-II InAs/GaSb superlattices using an empirical tight-binding method
and interface engineering
PHYSICAL REVIEW B 69, 085316 (2004)
?
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or from:
Phys. Rev. B 57, 6493–6507
Empirical spds* tight-binding calculation for cubic semiconductors: General method and material parameters
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There are definitely plans to include tight-binding models too in ATK, but it's a bigger job than just taking some parameters, as we could (hopefully) do for the extended Huckel model, which is already implemented. I found some nice papers with parameters for InSb and several other structures, I'm trying to see how we could include them.