how to calculate the band gap of graphene/mos2 heterostructure correctly

[njuxyh]

Hi:
i want to get the correct band gap of graphene/mos2 heterostructure,
one method is to use MGGA, but as the manual said, the c-parameter should test manual because the supercell have big vacuum region, because there are no corresponding bulk graphene/mos2, so the c-parameter can not be determined by known value as the manual said,
so i am wondering how to test the MGGA-c-parameter.
and another question is is there any better to calculate the band gap of such two-dimensional heterostructure in ATK?

THANK YOU VERY MUCH

[Ulrik G. Vej-Hansen]

The best alternatives are probably DFT-1/2 (same computational cost as GGA) and using PW with HSE06 (for reference calculations).

https://docs.quantumwise.com/tutorials/dft_half_pps/dft_half_pps.html

[Petr Khomyakov]

i want to get the correct band gap of graphene/...

Pristine graphene has a zero gap, which is protected by the symmetry of the graphene lattice - two carbon sublattice are equivalent - and that does not depend on the DFT functional you are using.

[njuxyh]

i want to get the correct band gap of graphene/...

Pristine graphene has a zero gap, which is protected by the symmetry of the graphene lattice - two carbon sublattice are equivalent - and that does not depend on the DFT functional you are using.

thank you, indeed prinstine graphene is gap-zero, but the MoS2/Graphene is non-zero small gap as many reference menthoned.

so i think it is depending on the the DFT functioanl useing maybe