Fix Move Rotation with sinusoidal law?

Hi there,

I am trying to impose a sinusoidal rotation to a region of my 2D simulations.
The idea is to do something related to oscillatory rheology.
I can create a probe, for example a square filled with particles with no force.
After that, I would like to rotate the the square of an angle following the evolution equation:

theta(t) = theta(0) * sin (w * t)

so that I will have an oscillatory deformation with amplitude that follow a sin law.

I have tried to explore

  • fix move

but those not seem to do what I want, since the rotation is continuos

  • displace_atoms

in principle i can make a loop to rotate the particle of a delta theta every # steps.
However, it does not appear to be a clean solutiom

Ideally I would need a fix semilar to move but with time evolution as in the equation above.

I probably can extend the fix move to do that, but I wanted to ask if you see a different way to do this (I am not a super-pro user).

Thanks in Advance