[Wien] What's the correct procedure for mBJ calculation

[Maciej Polak]

You shouldn't modify case.in0abp unless you really know what you're 
doing. Default parametrization usually works very well, and if you want 
to change it, try the options that are given to you during second 
init_mbj_lapw.

A difference that big means that there is probably something wrong 
earlier, especially if you don't have a very complicated case, you 
shouldn't get a difference bigger than 20-30% (usually less, e.g. GaAs 
is nearly perfect). Or if you have a very difficult material, read the 
mbjlda paper because maybe it doesn't work perfectly for your compound.

I would try getting either a confident crystallographic data or doing a 
proper geometry optimization once again. Both lattice constants and 
atomic positions greatly influence the band gap and overall band structure.

Or if you really want to change the "c" parameter (which I wouldn't do 
to solve a problem of 1.2eV difference), do it as it says in the 
userguide by modifying the grr file.

Best regards

Maciej Polak


On 11/14/2016 12:26 AM, Abderrahmane Reggad wrote:
> Thank you Mr Polak for your answer
> Yes, you are about the userguide as a unique reference.
>
> I have followed the procedure of the first reference and I got results.
>
> Another question:
>
> I have got a gap value of 1.3 ev for my compound which is bigger than the experimental
> value (0.1 ev) with the default value of  -1.200000000000000E-002
> for the c-parameter in the case.in0abp file.
>
> Which value of c , I got a gap value of 0.1 ev?
>
> Best regards
> -- 
> Mr: A.Reggad
> Laboratoire de Génie Physique
> Université Ibn Khaldoun - Tiaret
> Algerie
>
>
>
>
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