angular velocity coordinate

Thanks for the answer.

But I want to calculate the quaternion from angular velocity and calculate the rotational diffusion coefficient using the quaternions. I went to Python because I couldn’t find a way to do it in Lammps. In Python using function in the package pydiffusion. I was able to compute quaternion using angular velocity. But in this function there is a difference between the angular velocity in the center of mass of the object and the angular velocity in the coordinate of the laboratory.
So I want to know the omega chunck output in lammps are in center of mass coordinates or in lab coordinates .
The function is as follows:
def calc_quat(omega, q0, rate, CStype):
Take an angular velocity (in rad/s), and convert it into the
corresponding orientation quaternion.


I cannot tell for certain. you should find this information in the manual or in the source code.
but if you are not certain, would suggest to set up a test with a minimal input with just one molecule, where you set the per-atom velocities to generate a suitable rotation and then you can compare the result of what the compute in LAMMPS reports to what you can compute manually.


You can dump quaternions from lammps using dump custom. Would that help?