[ESPResSo-users] Fwd: Scaling of tabulated angular potentials

[Paul Peterson]

...does that mean that I SHOULD NOT divide by anything?

Put another way: should I just calculate the force as the derivative (with respect to theta) of the angular potential, without scaling factor, UNLIKE what I do with linear potentials?

Maybe this is the solution. In this way, the potential would be purely angular, that is, already independent of distance.

Any feedback?

Thanks in advance,

Paul 

---------- Forwarded message ----------
From: Paul Peterson <address@hidden>
Date: 2015-07-22 11:38 GMT+02:00
Subject: Re: [ESPResSo-users] Scaling of tabulated angular potentials
To: Rudolf Weeber <address@hidden>
Cc: ESPResSo Users <address@hidden>

Hi Rudolf,

thanks for your reply.

Your reasoning makes perfect sense, but the point is: when I define the tabulated angle potential I don't know what the distance (radius) will be. So what 1/r should I scale by?

Paul

2015-07-22 11:31 GMT+02:00 Rudolf Weeber <address@hidden>:

Hi Paul,
On Wed, Jul 22, 2015 at 11:07:24AM +0200, Paul Peterson wrote:
> I know this is not a new topic around here, but I've not been able to find
> an answer in these threads.
>
> I'm simulating a polymer with (among others) tabulated angular potentials.
> What is the 1/r scaling factor of force in this case? A distance doesn't
> seem to make much sense to me - distance is variable and depends on other
> potentials, of course.
> So what?
I think, the reasoning is that the energy U(theta) given by the potential should equal the integral of force times distnace over the path, a particle travles when the angle is increased from 0 to theta.
As the distance the particle travels increases when the radius is larger, the force has to be smaller.

Regards, Rudolf