where ε ε is the depth of the potential well and σ σ is the distance at which the potential crosses zero. The attractive term proportional to 1 / r 6 in the potential comes from the scaling of van der Waals forces, while the 1 / r 12 repulsive term is much more approximate (conveniently the square of the attractive term). On its own, this potential is quantitatively accurate only for noble gases and has been extensively studied in the past decades, but is also widely used for qualitative studies and in systems where dipole interactions are significant, particularly in chemistry force fields to describe intermolecular interactions - especially in fluids.