[ESPResSo-devel] Re: BOND_CONSTRAINT

[a_mait01]

Hi All

One can use bond contraint like this :

  inter 0 RIGID_BOND 1.51 1e-05 1e-05

where the bond length will be constrained to 1.51, and the positional and
velocity tolerance are each set to 1e-05. You may experiment with this value,
say 1e-3 etc. for faster convergence.

CAVEAT: I have not used Espresso for a long time and by now many changes have,
as expected, got incorporated into the programs. It will no more be feasible
for me to debug, if any unwanted changes had crept into the functions
contained in rattle.c. However, I recollect that the contraint had worked
properly for me for simulating PEO together with angle and dihedral
potentials, albeit slowing down the speed of computation.

I remember to have submitted a test case for "rattle" long back. May be it had
just got lost somewhere!! I found a test script which is about 2 years old and
had worked with an old version of Espresso. Please find them (*.tcl + *.data)
in the attachment and hope this solves the problem.

I am in middle of writing my phd thesis as I have to meet deadline and have
absolutely no time for exploring the functions that I myself had written
almost 3 years back. I would rather encourage the user to look into the Rattle
source code for rectifying/improving/improvising it to suit her/his needs.

Regards
Arijit

rattle.tcl
Description: Tcl script

rattle.data
Description: Binary data