  Event-driven molecular dynamics simulations are carried out on two rigid body
systems which differ in the symmetry of their molecular mass distributions.
First, simulations of methane in which the molecules interact via discontinuous
potentials are compared with simulations in which the molecules interact
through standard continuous Lennard-Jones potentials. It is shown that under
similar conditions of temperature and pressure, the rigid discontinuous
molecular dynamics method reproduces the essential dynamical and structural
features found in continuous-potential simulations at both gas and liquid
densities. Moreover, the discontinuous molecular dynamics approach is
demonstrated to be between 2 to 100 times more efficient than the standard
molecular dynamics method depending on the specific conditions of the
simulation. The rigid discontinuous molecular dynamics method is also applied
to a discontinuous-potential model of a liquid composed of rigid benzene
molecules, and equilibrium and dynamical properties are shown to be in
qualitative agreement with more detailed continuous-potential models of
benzene. Qualitative differences in the dynamics of the two models are related
to the relatively crude treatment of variations in the repulsive interactions
as one benzene molecule rotates by another.
