[CPMD-list] combination of PBE USPP with BLYP DFT

[Yi Liu]

----- Original Message -----
From: "Erik Emilio Santiso" <eesantis at unity.ncsu.edu>
To: "Jung Goo Lee" <jglee at nemo.physics.ncsu.edu>
Cc: <cpmd-list at cpmd.org>
Sent: Thursday, October 30, 2003 9:14 PM
Subject: Re: [CPMD-list] combination of PBE USPP with BLYP DFT


>
> Hi! Well, this looks more like a coincidence than anything else. I don't
> think it makes any sense to find a PP with one xc functional and then do
> the calculation with another one. What happens if you use the PBE PP's
> with the PBE functional?
>
> Erik.
>
> On Thu, 30 Oct 2003, Jung Goo Lee wrote:
>
> > Hi everyone,
> >
> > I would like to know whether the combination of PBE uspp in ATOMS option
> > and BLYP in DFT
> > option (the example of partial input is shown below)makes sense or not,
> > especially, for calculations
> > of free energy (constraint). This is because BLYP method underestimate
> > the dissociation free energy
> > compared with experiment. For example,  water dissociation in 32 water
> > molecules with MT PP/
> > BLYP method gave 17 kcal/mol in free energy while experimental value is
> > 21 kcal/mol(Trout and
> > Parrinello, Chem. Phys. Lett, 288(1998)343.
> > I tried the same calculation with PBE uspp and BLYP method.
> > I got about 20 kcal/mol althogh I tried with  a few hundred fs (instead
> > of 1 ps) MD at each point of
> > O-H bond constraint. So, this combination (PBE uspp/BLYP) seems to be
> > o.k. in free energy
> > calculations.
> >
> > Is this a reasonable and cheap(computationally) way to get out of the
> > problem with free energy
> > calculations with gbl uspp/BLYP?
> > Does any one have any rationalization or contradiction with reasonable
> > explanation?
> >
> > Jung-Goo Lee
> >
> > Example
> > --
> > --
> >  &ATOMS
> > *008-O-gpbe--bm.uspp NEWF BINARY
> >   LMAX=P
> >   1
> >   4.3728  4.5000  4.5000       1   8
> >
> > *001-H-gpbe--bm.uspp NEWF BINARY
> >   LMAX=S
> >   2
> >   5.5172  4.5000  5.9238       1   1
> >   5.5172  4.5000  3.0761       1   1
> > &END
> >
> > &DFT
> >  OLDCODE
> >  FUNCTIONAL BLYP
> >  GRADIENT CORRECTION BECKE88 LYP
> >  LDA CORRELATION LYP
> > &END
> > --
> > --
> >
> >
> > _______________________________________________
> > CPMD-list mailing list
> > CPMD-list at cpmd.org
> > http://www.cpmd.org/mailman/listinfo/cpmd-list
> >
> _______________________________________________
> CPMD-list mailing list
> CPMD-list at cpmd.org
> http://www.cpmd.org/mailman/listinfo/cpmd-list