  We generalize a simple Monte Carlo (MC) model for dilute gases to consider
the transport behavior of positrons and electrons in Percus-Yevick model
liquids under highly non-equilibrium conditions, accounting rigorously for
coherent scattering processes. The procedure extends an existing technique
[Wojcik and Tachiya, Chem. Phys. Lett. 363, 3--4 (1992)], using the static
structure factor to account for the altered anisotropy of coherent scattering
in structured material. We identify the effects of the approximation used in
the original method, and develop a modified method that does not require that
approximation. We also present an enhanced MC technique that has been designed
to improve the accuracy and flexibility of simulations in spatially-varying
electric fields. All of the results are found to be in excellent agreement with
an independent multi-term Boltzmann equation solution, providing benchmarks for
future transport models in liquids and structured systems.
