[Wien] mBJ potential for molecules?

[Ricardo Faccio]

Dear Prof. Blaha

Thanks, the idea is to absorb molecules on surfaces, so in this case the 
problem will not occur.

I used PRATT but without any success.

Thanks again.

Ricardo

-------------------------------------------------------------------------
  Dr. Ricardo Faccio
  Prof. Adjunto de Física
  Mail: Cryssmat-Lab., Cátedra de Física, DETEMA
  Facultad de Química, Universidad de la República
       Av. Gral. Flores 2124, C.C. 1157
       C.P. 11800, Montevideo, Uruguay.
  E-mail: rfaccio at fq.edu.uy
  Phone: 598 2 924 98 59
              598 2 929 06 48
  Fax:    598 2 9241906
  Web:  http://cryssmat.fq.edu.uy/ricardo/ricardo.htm
---------------------------------------------------------------------------------
----- Original Message ----- 
From: "Peter Blaha" <pblaha at theochem.tuwien.ac.at>
To: "A Mailing list for WIEN2k users" <wien at zeus.theochem.tuwien.ac.at>
Sent: Monday, August 02, 2010 11:40 AM
Subject: Re: [Wien] mBJ potential for molecules?


mBJ was designed for solids and it could well be that for a molecules the 
procedure
to determine a proper "c"-value (average of grad rho/rho) does not work and 
you get
unphysical values due to the vacuum region.

In such a case I can only recommend to remove case.in0_grr, and set
a proper grad rho/rho value in case.grr yourself.

A good estimate would be to set it to a similar value as a "similar" 
bulk-system
(eg. diamond) would have.

Also: Make sure you modified case.inm and set PRATT mixing !

Ricardo Faccio schrieb:
> Dear users
>
> I've been working on the isolated molecule catechol 
> (http://en.wikipedia.org/wiki/Catechol) in order to see how mBJ affects 
> its HOMO-LUMO gap.
>
> The initialization and convergence at GGA-PBE level went fine, obtaining a 
> energy gap of 4.0 eV in concordance with other DFT codes.
>
> Afther this I proceeded in order to incorporate the modified Becke-Johnson 
> potential (MBJ), but I found several problems in determining the position 
> of the Fermi level. What we see is a clear problem of finding enough 
> eigenvalues, which arelower than the number of valence electrons. 
> Therefore we proceed according to the userguide by:
> -changing the Fermi-Method (tetra, gauss and temp) -> error persist
> - changing Rmt to similar values increasing the lmax to12 -> error persist
> - increasing energy window in case.klist  and case.in1c in order to catch 
> the lost eigenvalues -> error persist
> It seems to be a problem on a big change introduced by the mBJ potential 
> which induces important divergences iat the  lapw1.
>
> ######################
>
> case.output1up
> ######################
>     EIGENVALUES ARE:
>       1.4443359    1.4892578    1.8037109    1.8486328    1.8486328
>       1.8935547    1.9384766    1.9384766
>          1923 EIGENVALUES BELOW THE ENERGY   -9.00000
>        ********************************************************
> The problem always occurs in the first cycle of the mBJ procedure after 
> lapw1, with few eigenvalues as you can see.
>
> I succeed applying this methodology to bulk systems such as TiO2.
>
> Any suggestion?
>
> Best regards
>
> Ricardo
>
>
> -------------------------------------------------------------------------
>   Dr. Ricardo Faccio
>   Prof. Adjunto de Física
>   Mail: Cryssmat-Lab., Cátedra de Física, DETEMA
>   Facultad de Química, Universidad de la República
>        Av. Gral. Flores 2124, C.C. 1157
>        C.P. 11800, Montevideo, Uruguay.
>   E-mail: rfaccio at fq.edu.uy <mailto:rfaccio at fq.edu.uy>
>   Phone: 598 2 924 98 59
>               598 2 929 06 48
>   Fax:    598 2 9241906
>   Web:  http://cryssmat.fq.edu.uy/ricardo/ricardo.htm
> ---------------------------------------------------------------------------------
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien

-- 

                                       P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: 
http://info.tuwien.ac.at/theochem/
--------------------------------------------------------------------------

_______________________________________________
Wien mailing list
Wien at zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien