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

[tran at theochem.tuwien.ac.at]

Hi,

0.06 eV from BJ is already very close to experiment and it does
not make sense to try to improve further the agreement.
Furthermore, the band gap is not the only quantity you should
consider for comparison with experiment.

FT

On Sunday 2016-11-20 22:34, Abderrahmane Reggad wrote:

>Date: Sun, 20 Nov 2016 22:34:57
>From: Abderrahmane Reggad <jazairdz at gmail.com>
>Reply-To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
>To: "wien at zeus.theochem.tuwien.ac.at" <wien at zeus.theochem.tuwien.ac.at>
>Subject: [Wien] How to get the experimental gap with mBj,
>    PBE+U and EECE methods
>
>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
>
>
>
>