[ghemical-devel] Tripos Parameters

[Geoffrey Hutchison]

On Aug 5, 2006, at 12:01 PM, Donald Ephraim Curtis wrote:

> Is there anyone here who happens to have a license with Tripos that  
> could call support and get the extended Tripos parameters.

I don't think that's likely. If parameterization is published, then  
it's public knowledge. But in the case of unpublished data, it's  
copyright by the author (i.e., Tripos).

If you want a Tripos-like force field, I can think of two alternatives:
* Changing the Ghemical code to substitute elements in the same group  
and use a different atomic radius / bond length. (Not great, but easy  
to do.)
* Reverse-engineering the parameters by evaluating the energy and  
geometry optimization of a range of Si compounds using Tripos.

> I have been contacted by a colleague who would like to get the Si  
> and other force fields into ghemical but the paper where the  
> original parameters came from doesn't include those fields.

As we discussed on the list before, there are a range of other, more  
modern force fields. UFF and MMFF94 come to mind. The latter even has  
a public test set:

http://ccl.net/cca/data/MMFF94/
http://ccl.net/cca/data/ff_evaluation_suite/

Cheers,
-Geoff