  The existence of coefficients for diffusion, viscosity and thermal
conductivity is examined for two-dimensional (2D) liquids. Equilibrium
molecular dynamics simulations are performed using a Yukawa potential, and the
long-time behavior of autocorrelation functions is tested. Advances reported
here as compared to previous 2D Yukawa liquid simulations include an assessment
of the thermal conductivity, using a larger system size to allow meaningful
examination of longer times, and development of improved analysis methods. We
find that the transport coefficient exists for diffusion at high temperature,
and viscosity at low temperature, but not in the opposite limits. The thermal
conductivity coefficient does not appear to exist at high temperature. Further
advances in computing power could improve these assessments by allowing even
larger system sizes and longer time series.
