Hi, I would like to add an external force f(x) on some atoms during the simulation, where x is the Cartesian coordinates of these atoms. Each component of the force can only be calculated with the whole set of coordinates, i.e., (f1, f2, ..., fn) = f(x1, x2, ..., xn) Is there a possible way to do it with Gromacs simply? Thank you! Ting