Gunnar Karlström

The anisotropic local electric fluctuations within a nanoscopic sphere of a polar fluid surrounded by vacuum are analysed using dielectric theory and molecular simulation. The electric fluctuations are characterized through the mean-square multipole moments (Q(l)(2)), which are related to the dielectric constant of the fluid. The results show that the fluctuations are suppressed close to the fluid boundary, with a stronger effect on the fluctuations perpendicular as compared to those parallel to the surface. Furthermore, the effect becomes weaker and more short-ranged as the order l of the fluctuating multipole moments is increased. The agreement between the results from dielectric theory and those from molecular simulations are satisfactory, in spite of the inhomogeneous density of the molecular system.