Thermodynamics of a one-dimensional self-gravitating gas with periodic   boundary conditions
  We study the thermodynamical properties of a one-dimensional gas with one-dimensional gravitational interactions, and placed in a uniform mass background. Periodic boundary conditions are implemented as a modification of the potential consisting of a sum over mirror images (Ewald sum), regularized with an exponential cut-off. The system has a phase transition at a critical temperature. Above the critical temperature the gas density is uniform, while below the critical point the system becomes inhomogeneous. Numerical simulations of the model confirms the existence of the phase transition, and are in good agreement with the theoretical results. 
Pankaj Kumar, Bruce N. Miller, and Dan Pirjol
cond-mat.stat-mech