Monte Carlo calculation of orientationally anisotropic pair distributions and energy transfer in a model monolayer

The NPT (number of particles, pressure, temperature) Monte Carlo method has been used to calculate the equation of state and orientation- and distance-dependent pair distributions for a model monolayer of hard "UFO"s. A UFO is defined to be the intersection volume of two identical spheres whose centers are more than one and less than two radii apart. As pressure is increased from zero, the UFOs rapidly tip perpendicular to the plane and then more gradually align. By use of the calculated equilibrium configurations, and Forster's orientation-dependent dipole-dipole energy-transfer rate constant, the bimolecular energy-transfer rate constant was calculated as a function of pressure and density. The macroscopic rate constant is sensitive to the extent of orientational ordering in the model monolayer.