how to get exact bandgap?

[HIMANIM]

Dear Sir,

I am trying to get exact experimental bandgap of bulk mos2 which is around 1.29 eV but I am getting a value of around 0.87 eV.
If i include quasi-particle correction in the ypp interpolation I get very high gap of around 3 eV.
What I am doing wrong or Am I not understanding anything?

Regards,
HImani Mishra
Research Scholar
IIIT Allahabad

[Daniele Varsano]

Dear HImani,
In general GW does not guarantee you match the experimental gap as GW it is an approximation. It is important you control the convergence of all parameters entering in your calculation in order to have the GW estimation of the gap, and it can differ from experiments. I'm not expert on MoS2, I know that it is a difficult task, but there are many papers in literature addressing this issue, probably also calculated with Yambo where you can check convergence parameters, SOC effects etc.

In any case, if you have gap of 0.87eV, the interpolation of the bands should continue not change it, otherwise it means something went wrong in the interpolation.

May be people experts in this class of system can provide you more help.

Best,

Daniele