On 12/10/2012 05:29 PM, Jason Swails wrote:
> The forces and energies are
> calculated in different subroutines on a per-restraint basis. If you are
> looking for a distance, look for the subroutine "disnrg" in nmr.F90. This
> is where the force (and its direction) are calculated. The direction comes
> at the end, where dfr(m) is calculated.
Thanks!
> Also note that, as per Newton's 3rd law, that the force
> exerted by the restraint on the first atom is the same, but opposite of
> that on the second atom.
The distance restraint system we're dealing with can be modeled by two
masses that are connected by a string, while none of the masses is in
fixed position and the length of the string varies over time, right?
This system is just superposed on top of the normal force field and
solved numerically. In this picture it is obvious that the spring
mediates symmetric forces acting on both atoms. Do we agree :-)?
> The code is a bit convoluted due to the numerous options and fairly complex
> mathematical form of the restraint potential, but the ideas are still
> there. You can look at angnrg, tornrg, etc. for how the forces are
> calculated and accumulated for the different types of restraints.
Thanks again :)
>
> HTH,
> Jason
>
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Received on Tue Dec 11 2012 - 03:30:02 PST
