[gmx-users] Three-site model for acetonitrile
christoph.freudenberger at chemie.uni-ulm.de
Mon Feb 24 16:31:33 CET 2003
Christoph Freudenberger wrote:
> I do not use any constraints. While double-checking the forcefield
> of MeCN i realized, I had set the bond length of the C-N triple bond
> to small (0.1nm instead of 0.116nm).
> Could that be the reason?
> I just started a simulation to find out...
The simulation is running now, and i looks like it really makes some
difference... But I have to wait for the longterm behaviour of the
system to be sure.
Just to get this thing complete:
What would be a good guess for the bond and angle force constants?
For now my acetonitrile.itp looks like this:
[ bonds ]
; ai aj funct c0 c1
1 2 1 0.14600 334720. ;C-C
2 3 1 0.11600 502080. ;C#N
[ angles ]
; ai aj ak funct c0 c1
1 2 3 1 180.0 418.400 ;C-C#N
The values were guessed by using the prodrg server. (BTW: Does anyone know
why the force constants for bonds given by prodrg are always factor 10
larger than the corresponding values in ffgmxbon.itp? Anyway, the values
I chose are consistent with ffgmxbon.itp.)
The values for the C-C single bond and the angle should be ok in my option,
but maybe the one for the C-N triple bond should be larger? The value
is equal to a C=O carbonyl bond.
Abt. Organische Chemie I AK Siehl - Uni Ulm -Tel: ++49-731-502-2785
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