Cluster sizes in a classical Lennard-Jones chain.

The definitions of breaks and clusters in a one-dimensional chain in equilibrium are discussed. Analytical expressions are obtained for the expected cluster length, 〈K〉, as a function of temperature and pressure in a one-dimensional Lennard-Jones chain. These expressions are compared with results from molecular dynamics simulations. It is found that 〈K〉 increases exponentially with β=1/k_{B}T and with pressure, P in agreement with previous results in the literature. A method is illustrated for using 〈K〉(β,P) to generate a "phase diagram" for the Lennard-Jones chain. Some implications for the study of heat transport in Lennard-Jones chains are discussed.