Re: [ESPResSo] Creation of Rigid Structures in Espresso

[Axel Arnold]

Am Donnerstag 29 Januar 2009 16:27 schrieb Lorenzo Isella:
> Dear All,
> My problem is that I would like to create e.g. a linear chain
> consisting of 8 particles. Each particle is connected e.g. to its left
> neighbor via a single contact point.
> Ideally, this chain should be a perfectly rigid body. What is the best
> way to create such a thing in Espresso? Should I use bond-angle
> interactions as described in the user guide or is there any better way
> for doing this?

Hi!

Currently, Espresso has a RATTLE implementation which can handle only rigid 
bonds with a fixed distance, which only allows by some tricks to form a 
truely stiff chain (using 1-2 bonds of length l and 1-3 bonds of length 2l), 
which probably would be very slow to  relax by RATTLE.

Therefore, I would indeed suggest to work with a rather stiff bond-angle 
interaction. Mehmet Sayar did some time ago simulations with relatively stiff 
polyelectrolytes, he can probably tell you reasonable parameters for time 
step and angle potential.

Axel

-- 
Dr. Axel Arnold 
Fraunhofer SCAI
Schloss Birlinghoven, 53754 Sankt Augustin, Germany
Tel: +49 2241 14 2575