Constrain all bonds in a polymer

Hi Users,

I would like to constrain all the bond lengths in a polymer while still allowing angles and dihedral rotation. I’ve looked into the shake fix but it seems it only allows small molecule constrains and the rigid fix seems it locks the entire molecule. Am I missing something? What would be the proper way to lock just bonds?

Thanks for the help,

You can't do that in LAMMPS. It's not a very parallel operation,
especially for long polymers, so we haven't implemented it.
You can use rRESPA which allows flexible bonds, with similar
long-timestep benefits to SHAKE.