Computer simulation of dipolar fluids. Dependence of the dielectric constant on system size: a comparative study of Ewald sum and reaction field approaches

We report Monte Carlo calculations on a Stockmayer fluid ( μ*=1, T*=1, ρ*=0.8) using both Ewald sum (EW) and reaction field (RF) approaches. We investigate the dependence of dielectric constant on system size. This dependence is less marked for EW than for RF. However, for a given number of particles the RF run time is substantially shorter. Both methods therefore offer some computational advantage. Overall, RF is to be preferred because of greater ease of programming.