[Wien] volume optimization

[tran at theochem.tuwien.ac.at]

mBJ should be used only for bulk solids (no vacuum). If there is
vacuum, then the calculation of the average of (grad rho)/rho in the
unit cell [see Eq. (3) in PRL, 102, 226401 (2009)] does not make any
sense. A solution would be to fix the value of c [Eq. (3)], but this
requires the modification of the subroutine vxclm2.f.

In case you want PBE-GGA total energy instead of LDA, you have to replace 

      exu=2.d0*(exupls + eclsd)
      exd=2.d0*(exdnls + eclsd)

by

      exu=2.d0*(exuppb + ecpbe)
      exd=2.d0*(exdnpb + ecpbe)

in vxclm2.f (below IGRAD .EQ. 28).


On Sun, 8 May 2011, Matthew Stream wrote:

> Dear Prof. Tran:
> thank you for your prompt reply.
> 
> > What is not possible, is to use forces for
> > the optimization of internal parameters.
> 
>   I got it.
> 
> > What do you mean by QW, QWR, QD?
>   QW :Quantum Well,
>   QWR:Quantum Wire, and
>   QD :Quantum Dot,
>   respectively.
>   Is the similar procedure you suggested applicable to these structures,
>   if I use super cells appropriately for them?
> 
> Thank you in advance.
> 
> Mat
> 
> -------- Original Message --------
> Subject: Re: [Wien] volume optimization
> From: tran at theochem.tuwien.ac.at
> To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
> Date: 2011/05/08 16:28
> 
> > Hello,
> >
> > When you use mBJ (number 28 in case.in0), the total energy is calculated
> > with LDA (i.e., the mBJ orbitals and electron density are plugged into
> > the LDA functional), and you can use this total energy for calculation of
> > energy vs. volume of unit cell. What is not possible, is to use forces for
> > the optimization of internal parameters. What do you mean by QW, QWR, QD?
> >
> > Hybrid functionals similar to HSE are in WIEN2k, but I don't know when it
> > will be released into the distributed WIEN2k version:
> > http://arxiv.org/abs/1103.4466
> >
> > F. Tran
> >
> > On Sun, 8 May 2011, Matthew Stream wrote:
> >
> > > Dear WIEN2k users and Prof. Blaha:
> > >
> > > Could you teach me if there's a way to calculate the Energy vs. volume
> > > curve for bulk, QW, QWR, QD (whatever, e.g. GaAs bulk crystal) with
> > > realistic band gap ( comparable to the experimental value)?
> > >
> > > As far as I know, mBJ is only a potential which is not applicable to the
> > > optimization, while HSE functional is not yet introduced into WIEN2k.
> > >
> > > Kind regards,
> > > Mat
> > > _______________________________________________
> > > Wien mailing list
> > > Wien at zeus.theochem.tuwien.ac.at
> > > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> > >
> > _______________________________________________
> > Wien mailing list
> > Wien at zeus.theochem.tuwien.ac.at
> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> >
> 
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> 
>