A key aspect of the MMVT protocol is the definition of Voronoi cells. When a system reaches one of the boundaries of the cell, it collides against the boundary, and the identities and timescales of these collisions are logged for eventual analysis. SEEKR2 leverages the powerful custom mathematical expressions within the OpenMM package in order to define the locations of Voronoi cells and boundaries. By supplying a mathematical expression, the user can define the boundaries of a Voronoi cell, and when the system crosses it, the integrator logs the crossing *5 information, the atomic positions and velocities are restored to the previous step, and velocities are reversed.