Fix rigid/minimize workaround

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1

Hi All,

I realized after the fact, that the fix rigid does not work with minimize. Is there any workaround that won’t distort the bonds on the rigid particles?

Thanks,

Fred

2

In case it is of use to someone else, someone gave me a good answer to this question which uses “fix setforce”. It works when unoverlapping is the only objective …

To the rigid molecule(s) apply:

fix freeze RIGIDSTUFF setforce 0.0 0.0 0.0

  • other fixes

minimize …

unfix freeze

fix N RIGIDSTUFF rigid molecule

…

3

Getting the minimizers to work with constraints like
SHAKE or fix rigid is non-trivial. I don't know how
to do it correctly. So LAMMPS doesn't do it.

Steve