[Wien] mBJ and the states in the energy gap

[tran at theochem.tuwien.ac.at]

Hi,

this paper:
http://journals.aps.org/prb/abstract/10.1103/PhysRevB.89.125429
is about the F center in LiF. The mBJ band gap for LiF is good (Table II),
but Figure 3 shows that the energy position of the electron at the vacancy
is quite different with mBJ compared to the other methods. So, good band
gap does not automatically mean good intergap states. Using Hybrid
functionals is an alternative, but they are expensive.

F. Tran


On Thu, 30 Oct 2014, Nikola Novakovic wrote:

> Hello all, 
> I am running simple supercell calculations of MgH2 with H vacancies. The
> purpose of these calculations is to obtain changes in optical properties due
> to existence of H vacancies in this system. Since obtaining the proper
> energy gap is essential, I have tried both scissor shift and mBJ method. mBJ
> is giving excellent agreement with experiment, however I am not sure if the
> position of vacancies intergap states is good. Scissor shift results looks
> more reasonable, according to obtained influence of gap states to the
> visible part of spectrum. Does anyone know just how good the mBJ is for
> description of states in the gap? If it is not, what can be done to improve
> the description of these states (using Wien2k)?
> 
> Thanks in advance,
> 
> Novakovic Nikola
> 
> 
>