The ABINIT Users Mailing List ( CLOSED )

[Nicola Marzari <marzari@MIT.EDU>]

Dear Nuno, Kai,

we have recently looked at this, and found the Barone functional
(for our own case) qualitatively very similar to PW91:

Pi-Stacking in Charged Thiophene Oligomers,
Scherlis, D. A.; Marzari, N.;
J. Phys. Chem. B. ; (Article); 2004; 108(46); 17791-17795.

Weak interactions, or open-shell system, often require
accurate but expensive quantum chemistry approaches; although
it's still a very open field and topic...

Best,

                        nicola




Nuno A. G. Bandeira wrote:
> forum-request@abinit.org wrote:
>
> > A question for the ABINIT experts:
> > I want to calculate two weakly interacting molecules. What functional 
> > should be used in such case ? Is there any published work done with
> > ABINIT for such systems ?
> > With appreciation of any comments
> > Sincerly Kai Braun
> >
> > Research Assistant Professor
> > Ohio University
>
>
> The Perdew-Wang 91 functional is usually sensitive to weak interactions 
> because it has a fairly good description of exchange at long distances.
>
> A modified version of this functional by Barone is especially tuned for 
> those types of interaction but this is only present in other packages 
> like Gaussian or ADF.
>
> I would avoid using Becke88 based functionals with weak closed shell 
> interactions.

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