Classical simulation codes typically contain a good selection of analytical forms for describing atomic interactions. Sometimes however, you may need to use a potential that is not directly supported by the code. Luckily, most simulation codes allow you to provide tabulated potentials in which energies and forces, for a range of interatomic separations, are pre-calculated and specified as rows within a text file. The atsim.potentials package provides python modules to make the specification and tabulation of pair- and many-body potentials straightforward and consistent.