  The manner in which the intermolecular potential u(r) governs structural
relaxation in liquids is a long standing problem in condensed matter physics.
Herein we show that diffusion coefficients for simulated Lennard-Jones m-6
liquids (8<m<36) in normal and moderately supercooled states are a unique
function of the variable rho^g/T, where rho is density and T is temperature.
The scaling exponent g is a material specific constant whose magnitude is
related to the steepness of the repulsive part of u(r), evaluated around the
distance of closest approach between particles probed in the supercooled
regime. Approximations of u(r) in terms of inverse power laws are also
discussed.
