MOLECULAR-DYNAMICS CALCULATION OF THE DIELECTRIC-CONSTANT WITHOUT PERIODIC BOUNDARY-CONDITIONS .1.

We outline the difficulties in obtaining a reliable value of the dielectric constant of a fluid using molecular dynamics calculations with periodic boundary conditions, and give some explanation of the observed asymptotic behaviour of hD(r) and hΔ(r) in Monte Carlo simulations of dipolar hard spheres. An alternative method consisting in simulating a dielectric in vacuum is described. This is applied to two dimensional systems. The pertinent theoretical relations for a dielectric disc in vacuum are therefore derived. It is concluded that relations involving MC or MD computation of <m2> must be carefully handled. © 1979 Taylor & Francis Ltd.