[Wien] New exchange-correlation potential

[F. Tran]

Which value do you obtain? Did you use the correct structure?
In Table 1 of the following paper:
Tran et al., J. Phys.: Condens. Matter 19, 196208 (2007)
it is indicated which structure and lattice constant were used.

In case.inm_vresp, you have to replace YES by NO for the normalization.


On Wed, 9 Jun 2010, yhzhao wrote:

> Hi,
> I have do all your suggested things, which given in the usersguide. However I
> cannot get the band gap, that is 1.64 eV for GaAs, as suggested by PRL 102,
> 226401 (2009).
> 
> 
> yonghong
> On 2010年06月09日 17:54, F. Tran wrote:
> > Hello,
> >
> > In order to use the modified Becke-Johnson exchange potential
> > you have to choose indxc=28 in case.in0 and indxc=50 in case.in0_grr.
> >
> > A few more things:
> >
> > In case.in0 you also need to replace NR2V by R2V such that the
> > exchange-correlation potential is written in case.r2v, which will
> > be used in the next iteration.
> >
> > You need case.inm_vresp such that case.vrespsum (which contains a
> > part of the kinetic-energy density) is created.
> >
> > There is no adjustable parameters.
> >
> > The LDA correlation potential is added to the MBJ exchange potential.
> >
> > The LDA exchange-correlation functional is used for the energy.
> >
> > The MBJ exchange potential is not the derivative of an energy functional,
> > which means that the method is not variational (i.e., the orbitals are
> > not the ones which minimize the total energy, which is LDA).
> > In particular, it means that you can not use forces to optimize internal
> > parameters.
> >
> >
> > On Wed, 9 Jun 2010, yhzhao wrote:
> >
> >    
> > > Dear Prof. Pblaha,
> > >
> > > I have tried to calculate something using the new exchange potential
> > > with indxc=50 as suggested by the usersguide. At first I want to repeat
> > > some data given by PRL 102, 226401 (2009), for example, the band gap of
> > > GaAs. I can get a band gap of 0.7 eV for GaAs, which is much better than
> > > 0.3 eV of lda, but not much better than the value given by you in PRL
> > > 102, 226401 (2009). In the calculation, I use the experimental lattice
> > > constant. The k-grid have been increased as dense as 20x20x20 and RKmax
> > > as large as 9.0.
> > >
> > > Is there any adjustable parameter for the MBJ calculation? Thanks.
> > >
> > > Regards,
> > >
> > > yonghong
> > >
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