[gpaw-users] PW91 functional

[Jens Jørgen Mortensen]

On Thu, 2010-04-22 at 09:19 -0500, Nichols A. Romero wrote:
> JJ,
> 
> I will give that a try.
> 
> But I am still surprised by the behavior, for norm-conserving pseudopotential
> I would not expect this. An unscreened PW91 and unscreened PBE pseudopotential
> should give virtually the same results. But I do not know if this is also
> applicable to PAW with all the projector functions, compensating charges, etc.

This is not surprising.  Try this:

  gpaw-setup -a -f PBE Zr

and

  gpaw-setup -a -f PW91 Zr

You will see an energy difference of 17.9 eV.  Since GPAW gives you
energies relative to the reference atom energies, which it reads from
the setup files you will get en energy shift of 17.9 eV.  I think this
is what you are seeing.

JJ

> Nichols A. Romero, Ph.D.
> Argonne Leadership Computing Facility
> Argonne National Laboratory
> Building 240 Room 2-127
> 9700 South Cass Avenue
> Argonne, IL 60490
> (630) 252-3441
> 
> 
> ----- "Jens Jørgen Mortensen" <jensj at fysik.dtu.dk> wrote:
> 
> > On Thu, 2010-04-22 at 08:01 -0500, naromero at alcf.anl.gov wrote:
> > > JJ,
> > > 
> > > I enclose a .tar.gz with the input file and some results. Note that
> > I made the symbolic link in my setups directory
> > > 
> > > ln -sf Zr.PBE.gz Zr.PW91.gz
> > 
> > OK, I see.  I would also recommend that you use a real PW91 setup.
> > 
> > JJ
> > 
> > > It is a Zr in hcp, but with no k-points (which doesn't make too much
> > sense, but should be fine for this test).
> > > 
> > > I agree that it is all about energy differences. But the absolute
> > value of the total energies should not be varying by this much. Also,
> > a positive total energy is just
> > > as weird.
> > > 
> > > Nichols A. Romero, Ph.D.
> > > Argonne Leadership Computing Facility
> > > Argonne National Laboratory
> > > Building 240 Room 2-127
> > > 9700 South Cass Avenue
> > > Argonne, IL 60490
> > > (630) 252-3441
> > > 
> > > 
> > > ----- "Jens Jørgen Mortensen" <jensj at fysik.dtu.dk> wrote:
> > > 
> > > > On Thu, 2010-04-22 at 07:22 -0500, Nichols A. Romero wrote:
> > > > > Michael,
> > > > > 
> > > > > So you are saying that you would expect 
> > > > > PBE total energy = 4 * PW91 total energy
> > > > 
> > > > Could you show us exactly what you are doing?
> > > > 
> > > > JJ
> > > > 
> > > > > This was for a two-atom cell.
> > > > > 
> > > > > That seems quite large... even for a total energy. You don't
> > even
> > > > see
> > > > > that kind of 
> > > > > a difference between PBE and LDA.
> > > > > 
> > > > > Nichols A. Romero, Ph.D.
> > > > > Argonne Leadership Computing Facility
> > > > > Argonne National Laboratory
> > > > > Building 240 Room 2-127
> > > > > 9700 South Cass Avenue
> > > > > Argonne, IL 60490
> > > > > (630) 252-3441
> > > > > 
> > > > > 
> > > > > ----- "Michael Walter" <Michael.Walter at fmf.uni-freiburg.de>
> > wrote: 
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > 2010/4/21 Nichols A. Romero <naromero at alcf.anl.gov>
> > > > > > 
> > > > >         Hi,
> > > > >         > 
> > > > >         > Someone at Argonne is interested in doing a
> > calculation
> > > > with
> > > > >         PW91 GGA functional
> > > > >         > 
> > > > >         > I performed a test with xc='PW91' and re-using a PBE
> > > > setup
> > > > >         but the energies seemed crazy. They were 4 times lower
> > in
> > > > >         energy than the corresponding LDA/PBE calculation.
> > > > >         > Does any one have any idea as to what might be going
> > on?
> > > > >         > 
> > > > > 
> > > > > > Better use also the PW91 setup. While the total energies
> > differ a
> > > > > lot, the relative energies are very similar to PBE in my
> > > > experience.
> > > > > > 
> > > > > > Michael
> > > > > > 
> > > > > > 
> > > > >         
> > > > >         > Nichols A. Romero, Ph.D.
> > > > >         > Argonne Leadership Computing Facility
> > > > >         > Argonne National Laboratory
> > > > >         > Building 240 Room 2-127
> > > > >         > 9700 South Cass Avenue
> > > > >         > Argonne, IL 60490
> > > > >         > (630) 252-3441
> > > > >         > 
> > > > >         > _______________________________________________
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> > > > >         >
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> > > > >         > 
> > > > > 
> > > > > > 
> > > > > 
> > > > > > -- 
> > > > > > ------------------------------------------
> > > > > > Michael Walter  
> > > > > > Address: Freiburger Materialforschungszentrum
> > > > > >         Stefan-Meier-Straße 21 
> > > > > >         D-79104 Freiburg i. Br.
> > > > > >         Germany
> > > > > > Tel.: +49 761 203 4758 and +49 761 203 7695
> > > > > > Fax: +49 761 203 4701
> > > > > > email: Michael.Walter at fmf.uni-freiburg.de
> > > > > > www: http://omnibus.uni-freiburg.de/~mw767
> > > > > > 
> > > > > > 
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