Finite-size effects in Monte Carlo simulations of the Gaussian disorder model

We study theoretical issues related to the use of finite size systems in Monte Carlo simulations of the Gaussian disorder model (GDM). The GDM is one of the most widely used models to describe the charge transport in random organic materials. In the GDM, the energy of charge carriers is well known to approach an equilibrium energy in the long-time limit. We find that at low temperatures, the equilibrium energy shows a strong dependence on the system size. Using improved numerical methods, we study system sizes much bigger than those used in earlier works. We show that, below a certain temperature, a system size much larger than those used in conventional studies must be used to correctly describe the temperature dependence of the equilibrium energy.