Bulk MoS2 band gap

[Manish95]

Hi,

I am using QuantumATK 2017.2 version. I am doing band structure calculation for bulk MoS2. I am using ATK-DFT: LCAO, GGA-PBE exchange-correlation, 75 Ha mesh cutoff, 8x8x8 k point, OMX pseudopotential with Medium basis set. But I get band gap 0.89 eV rather than 1.2 eV.

[Ulrik G. Vej-Hansen]

Could you please explain why you expected 1.2 eV? Is it from a reference where the same computational parameters were used?

Have you converged your calculation with respect to the various computational parameters?

[Manish95]

1.2 eV is the experimental value for bulk MoS2 (Zhiming, MoS2 Materials, Physics and devices).  I have converged the calculation.

[Jess Wellendorff]

0.89 eV is what you would expect for bulk MoS2 if using a LDA or GGA density functional, there are many examples in literature, see e.g. https://file.scirp.org/pdf/Graphene_2014102014384642.pdf

[Petr Khomyakov]

In addition to the previous post, the band gap is also sensitive to the separation distance, see PHYSICAL REVIEW B 87, 245114 (2013). In the latter, one can also find a comparison of DFT-calculated band gaps to that of GW. The largest gap the authors report with DFT does not exceed 1 eV, see Fig. 4 in the paper.

I also note that stacking of MoS2 monolayers would also affect the band gap value.