A lambda transition in a classical electron film

A 10000 particle molecular-dynamics computer model, using the PPPM method, has been used to study a system of classical electrons confined to move in a plane. This is a realistic model of electrons at low densities bound in external surface states on liquid helium. A lambda-type phase transition has been observed at a temperature Tt, and density, n, for which Gamma 0= phi 12/n12/e2/kTt=95+or-2. The transition has an associated internal energy change of 1.1 k/electron and is between a poly-microcrystalline solid phase and a liquid phase. On the low temperature side, the gradual rise of specific heat (Cv approximately (- epsilon )-0.08. epsilon =(T-T1)/T1) is associated with a gradual decrease of crystallite size. On the high temperature side there is a sharp drop in specific heat, following roughly Cv approximately ( epsilon )-0.14, to a state with a distribution function characteristic of a liquid.