[gmx-users] rigid body

[Ram'on Garc'ia Fern'andez]

I don't think Gromacs supports rigid bodies. However, you can achieve a similar
result using enough constrains between the atoms involved; and removing forces
between them. That will not be as efficient as a program that supports rigid bodies;
but it might be enough.

Supporting rigid bodies would make the code more complex, because the
physics of a rigid body are more complex than the physics of
atoms. Compared to atoms, rigid bodies do have orientation in addition
to position, torques in addition to forces and rotation in addition to
traslation.

In addition, there might be subtle problems related to the metric tensor
so that even using constrains in a molecule that has a flexible part
might be incorrect. You should check this.

Ramon