Hard Disks in Narrow Channels
  The thermodynamic and dynamical behavior of a gas of hard disks in a narrow channel is studied theoretically and numerically. Using a virial expansion we find that the pressure and collision frequency curves exhibit a singularity at a channel width corresponding to twice the disk diameter. As expected, the maximum Lyapunov exponent is also found to display a similar behavior. At high density these curves are dominated by solid-like configurations which are different from the bulk ones, due to the channel boundary conditions. 
Ch. Forster, D. Mukamel, and H. A. Posch