[gmx-users] Three-site model for acetonitrile

[David]

On Tue, 2003-02-25 at 21:43, Christoph Freudenberger wrote:
> 
> 
> christoph.freudenberger at chemie.uni-ulm.de wrote:
> > Zitat von David <spoel at xray.bmc.uu.se>:
> >>Probably not... The constraints (and bonds) can only exert forces along
> >>the bonds, and hence it is rather ineffecient/impossible to move the
> >>central carbon back on the bond once it moves off there...
> > 
> > Ok, I'll forget about that... 
> 
> Accually I can't really forget it... what if i used the three atoms
> and constrain them with a massless interactionless dummy:
> something like this:
> 
> Me--C--N
>    \ | /
>     \|/
>      D
> 
> if the dummy has no mass, charge and vdw the nature of the molecule
> should no be altered, right?
The problem here is how to define the dummy, since it must either be a
linear cobination of the constituting atoms (which can not go off the
bond) or something with a cross product, but that wouldn't work either
since the two vectors you have in that case are linearly dependent...

> 
> regrads
> -- 
> Christoph Freudenberger
> Abt. Organische Chemie I AK Siehl - Uni Ulm -Tel: ++49-731-502-2785
> 
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-- 
Groeten, David.
________________________________________________________________________
Dr. David van der Spoel, 	Dept. of Cell and Molecular Biology
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
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