[Wien] How to get the experimental gap with mBj, PBE+U and EECE methods

[Abderrahmane Reggad]

Dear Wien Users

I have a material with an experimental gap value of 0.1 ev and when using
different methods I found values far from this value as follows:

* mBJ method:
****************
- The original BJ parametrization : Eg=0.06 ev ---> There is no parameter
to manipulate

- The modified BJ parametrization of P.Blaha and F.Tran: Eg= 1.3 ev --->
Which values for alpha and beta to get the experimental value?

- The others parametrizations give a similar value as for mBJ
parametrization.

* PBE+U (U=3 ev):
*******************

Eg=1.5 ev ----> We can't go under 3 ev for U to maintin the
antiferromagnetic state .

* EECE method:
******************

The two values for alpha (0.25 and 0.1 ) give the same value of gap which
1.5 ev.

How to sove this problem?

NB: The PBE method gives no gap

Best regards

-- 
Mr: A.Reggad
Laboratoire de Génie Physique
Université Ibn Khaldoun - Tiaret
Algerie
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