Rotation of group of particles about its own axis, fix move

LAMMPS LAMMPS General Discussion
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1

Hello,
I need to do rotation of a group of particles about its center of mass direction using fix move command.
Say for example how to rotate six beads sitting at the vertices of a hexagon connected by three body interactions, about its COM? I know that, particles can be grouped and can be rotated about X-axis (100)or Y or Z using fix move rotate. Note I don’t want to consider hexagon as a rigid body hence no need to use fix rigid.

I appreciate your help.

Thanks,
Rahul M

2

Using fix move on those atoms will produce a rigid body motion just like fix rigid.
You cannot have a fully prescribed motion without suppressing other motions in LAMMPS.

Otherwise you can just add a force that will cause a rotation, which can be done with fix addtorque.

Please search through the archives because this topic has come up a couple times and I have produced two different examples for such “prescribed” motion cases.