A potential used to give an approximate description of the potential energy interaction, V, of molecules as a function of intermolecular distance r. The general form of the Lennard–Jones potential is

where C_n and C₆ are coefficients that depend on the specific molecules and n is greater than 6 so that at small separations the repulsion term dominates the interaction, the r⁻⁶ term being attractive. The value n = 12 is frequently chosen. In this case the Lennard–Jones potential is given by:

where W is the depth of the potential well and r₀ is the separation at which V = 0. The minimum value of the well occurs at the separation r_e = 2^1/6r₀. The representation of the repulsive part of the interaction by a 1/r¹² term is not realistic; a much more realistic term is the exponential term, exp(–r/r₀), as it is closer to the exponential decay of the wave functions and thus of their overlap, which describes the repulsion. The Lennard–Jones potential was devised by the British theoretical chemist Sir John Lennard–Jones (1894–1954) in 1924.