[gmx-users] Using Morse potentials with ENCAD force field

[David van der Spoel]

Andy Shelley wrote:
> I have added a mixture of oxgen and nitrogen to a simulation with a 
> cnt.  The oxygen and nitrogen use morse potentials and the cnt uses the 
> encad force field. Previously I simulated the cnt with the default water 
> and it worked well.  When using my "air" mixture the cnt collapses even 
> if a small number of molecules is added.  The values I am using for the 
> potentials are:
>                           N-N       O-O
> b0 (nm);            0.1098    0.1207
> D (kJ mol-1);    941.692   493.50
> Beta(nm-1)        26.42       26.80
> 
> Do these values seem right and is there anything I should be aware of 
> with my setup?
The morse bit could be right, but how about the non-bonded interactions 
between air and CNT? I don't understand why you would use Encad for the 
CNT either, although it may be quite similar to other force fields in 
practice.

> 
> Thanks,
> Andy
> 
> 
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-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
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://folding.bmc.uu.se
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