  In condensed matter physics, particularly in perovskite materials, the
rotational motion of molecules and ions is associated with important issues
such as ion conduction mechanism. Constrained Molecular Dynamics (MD)
simulations offer a means to separate translational, vibrational, and
rotational motions, enabling the independent study of their effects. In this
study, we introduce a rotational and roto-translational constraint algorithm
based on the Velocity Verlet integrator, which has been implemented into a
homebrew version of the CP2K package. The MD results show that our program can
selectively constrain the molecules and ions in the system and support
long-time MD runs. The algorithm can help the future study of important
rotation related dynamic problems in condensed matter systems.
