Spherical Boundary Conditions: A Finite and System Size Independent Geometry for Simulations of Electrolytic Liquids

摘要

The system size dependence of the thermodynamic properties of electrolytic systems in "Spherical Boundary Conditions" (SBC) have a been examined in this work. Coulombic systems were simulated with different system sizes (N) for a wide range of concentrations, different ionic charges and solvent permittivities. The effects of system size upon the mean internal energy and mean ionic activity coefficient <γ±> values were determined. our results indicated that there was no dependence of the thermodynamic properties upon system size in the non-Euclidean geometry. Different methods of extrapolating the thermodynamic properties to infinite numbers were studied in detail. In contrast to the Euclidean geometry, the method of extrapolating or <γ±> versus N~(-1), N~(-2/3) and N~(-1/3) was not statistically justifiable nor advantageous. Therefore, SBC is well suited to simulating systems involving long-range electrostatic interactions because the results do not dependent upon system size.