Re: [ESPResSo-users] Individual Forcecap

[Axel Arnold]

On 04.04.14 16:49, roya moghaddasi wrote:

I want to warm up my system. During warm up I want to cap the LJ potential between the particles but not between the constraint and the particles, when I do so, I face the following error:

bond broken between particles....

(If I cap all the interactions it runs well.)

I've changed the FENE parameters but it didn't help. I don't know how to solve this problem. I would appreciate if someone could help me.

We also cannot solve the problem for you. We have suggested several ways of warming up the system, but it seems that you cannot stably bring the system to equilibrium. There are three possible causes:

- your parameters are unphysical, e.g. lead to too high local densities. Since you constrain particles on a circle, that might well be the case, although I find it unlikely.

- you are just not patient enough and need just much more time steps for warming up, as Peter several times suggested.

- the way you warm up your system still leaves enough configurations of too high interaction energy. Capping is essentially a way of cutting off all these, another possibility is to not set up the particles at random, but rather such that you know that there are no critical overlaps. There have been a number of suggestions for you on this mailing list, and you can try to combine them, till you find a viable route.

We cannot figure out for you what is the cause, since we cannot run the simulations ourselves. However, I am pretty confident that if your system is physical at all, you can warm it up reliably with the methods suggested earlier on this list.

Axel

-- 
JP Dr. Axel Arnold
ICP, Universität Stuttgart
Allmandring 3
70569 Stuttgart, Germany
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Tel: +49 711 685 67609