LARGE DEVIATIONS FOR CLUSTER SIZE DISTRIBUTIONS IN A CONTINUOUS CLASSICAL MANY-BODY SYSTEM

An interesting problem in statistical physics is the condensation of classical particles in droplets or clusters when the pair-interaction is given by a stable Lennard Jones-type potential. We study two aspects of this problem. We start by deriving a large deviations principle for the cluster size distribution for any inverse temperature beta is an element of (0, infinity) and particle density rho is an element of (0, rho(cp)) in the thermodynamic limit. Here rho(cp) > 0 is the close packing density. While in general the rate function is an abstract object, our second main result is the Gamma-convergence of the rate function toward an explicit limiting rate function in the low-temperature dilute limit beta -> infinity, rho down arrow 0 such that -beta(-1) log rho -> nu for some nu is an element of (0, infinity). The limiting rate function and its minimisers appeared in recent work, where the temperature and the particle density were coupled with the particle number. In the decoupled limit considered here, we prove that just one cluster size is dominant, depending on the parameter nu. Under additional assumptions on the potential, the Gamma-convergence along curves can be strengthened to uniform bounds, valid in a low-temperature, low-density rectangle.