  Simulations of charge transport in amorphous semiconductors are often
performed in microscopically sized systems. As a result, charge carrier
mobilities become system-size dependent. We propose a simple method for
extrapolating a macroscopic, nondispersive mobility from the system-size
dependence of a microscopic one. The method is validated against a
temperature-based extrapolation [Phys. Rev. B 82, 193202 (2010)]. In addition,
we provide an analytic estimate of system sizes required to perform
nondispersive charge transport simulations in systems with finite charge
carrier density, derived from a truncated Gaussian distribution. This estimate
is not limited to lattice models or specific rate expressions.
