Consistent calculation of the static and frequency-dependent dielectric constant in computer simulations

Abstract

Recently a computer adapted theory suitable for evaluating the dielectric properties of polar systems has been proposed. It rests on the assumption that the system behaves like a macroscopic dielectric and that the modifications of dipolar interactions do not affect its dielectric constant. In the present paper these assumptions are tested, for a system of 512 Stockmayer particles with μ*² = 3·0 and I* = 0·025 at ρ* = 0·822 and T* = 1·15, in a series of extensive simulations, in which the boundary conditions (spherical reaction field (RF) vs. lattice summation technique (LS)) have been varied in a systematic way. Within the limits of statistical accuracy all simulations give identical results for the static as well as for the frequency dependent dielectric constant, namely ε(0) = 66 and a relaxation time of τ_D* ≃ 1·0 for the almost Debye-like behaviour of ε(ω). For particle numbers of 256 and upward the system studied behaves like a macroscopic dielectric; the bulk dielectric constant is independent of N for RF as well as LS-geometry.