THE FREEZING OF SOFT SPHERES FROM A SIMPLE HARD-SPHERE PERTURBATION-THEORY

It is shown that a simple perturbation expansion around the free energy of a (BCC/FCC) hard-sphere crystal leads to accurate predictions for the (BCC/FCC) freezing of soft spheres interacting via the inverse-power potential, V(r) = epsilon(sigma/r)n, for all values of n including the extreme case of the one-component plasma (n = 1). In particular, we find that for 1 less-than-or-equal-to n less-than-or-equal-to 6 there is both a fluid-BCC and BCC-FCC transition whereas for n > 6 the BCC phase is unstable and only the fluid-FCC transition survives, in agreement with the computer simulations.