NAMD 2.6 & 2.7:

• RAMD scripts and example files can be downloaded here as a tar file
  The Random Acceleration Molecular Dynamics (RAMD) method can be used to carried out molecular dynamics simulations with an additional randomly oriented force applied to the center of mass of one molecule in the system. It can be used, for example, to identify egress routes for a ligand from a buried protein binding site. For more information on RAMD, see the RAMD webpage