Re: [cclib-devel] Morokuma EDA analysis

[Karol L. <kar...@kn...>]

I'd like to return to the threads that I didn't have time to answer to in the 
past month... this one I'm interested in especially, since my research 
involves also interaction energy calcualtions.

On Monday 30 July 2007 02:54, Noel O'Boyle wrote:
> Sure, Morokuma decomposition would be great. In fact, I was looking
> for this a couple of years ago during my PhD. I think that it's built
> into GAMESS, but not in Gaussian, so I tried to run my calculation
> with GAMESS but it failed to converge. And that was the end of that...

Yes, the Morokums decomposition scheme, and a few variants of it, are 
implemented in GAMESS.

> On 25/07/07, Karol Langner <kar...@kn...> wrote:
> > >>> Hi,
> > >>>
> > >>> Has anyone considering implementing Ziegler-Morokuma energy
> > >>> decomposition analysis into cclib? I don't know everything that is
> > >>> involved in the calculation off hand, but I don't think it would
> > >>> be an
> > >>> enormous job considering that CDA is already implemented. It's
> > >>> something
> > >>> I would consider doing, once I'm done with the turbomole binding.
> > >>>
> > >>> Chris
> > >>
> > >> I would be very interested in this, but I don't share your enthusiasm
> > >> about how easy it would be.
> > >>
> > > I must admit I've never heard of this EDA. How does it differ from
> > > CDA, and what exactly is involved? Do you have a link to a paper or
> > > website?

A good overview of the methodology is in this paper by the people from GAMESS 
and many relevant references therein:
"Energy decomposition analysis for many-body interactions,
 and application to water complexes"
W.Chen, M.S.Gordon   J.Phys.Chem. 100, 14316-14328(1996)

The thing is, for EDS you need the overlap and Fock matrices. You don't 
normally have the Fock matrix in the output of programs. You could construct 
it by yourself, then you need to calculate two-electron Coulumbic repulsion 
integrals for the system. Although PyQuante does this, it would probably be a 
bottleneck (not sure how small).

With that said, I still think it is worthwhile to try to get this implemented, 
since decompositions are used alot and don't have that many implementations. 
It would be great to be able to do them for output from a number of programs!

Cheers,
Karol

-- 
written by Karol Langner
Fri Aug 17 18:51:42 EDT 2007