[gmx-users] force constants

[Anton Feenstra]

Arturas wrote:

> Hi,
> 
> I am wondering how force constants are derived for various FF in
> GROMACS. I want to get the force constant for Fe=O bond. I tested C=O
> force constant for Fe=O in my model and it worked well. Now I want to
> supply Fe=O bond parameters for FF, which are right for that model.

They are normally irrelevant, since bonds are constraint to a fixed length. 
I would be surprised if anybody in the last years actually spent time 
optimizing them in the Gromos forcefields.

Probably, they derive directly from (very) early forcefields, and would 
indeed mostly be based on IR frequencies. I don't think they were ever 
optimized to any extent to tune MD results.


-- 
Groetjes,

Anton
  _____________ _______________________________________________________
|             |                                                       |
|  _   _  ___,| K. Anton Feenstra                                     |
| / \ / \'| | | Dept. of Pharmacochem. - Vrije Universiteit Amsterdam |
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