Dielectric response with short-ranged electrostatics

Significance Much of a liquid’s ability to act as a solvent stems from its dielectric properties. The intermolecular forces between polar molecules can act over very long ranges, which complicates both theoretical descriptions and molecular simulations. Here the dielectric properties of a model system with only short-ranged intermolecular interactions are investigated, and this short-ranged model’s behavior is rationalized on a theoretical basis. This work will likely facilitate the development of both efficient short-ranged interaction potentials and our understanding of fluids under confinement. The dielectric nature of polar liquids underpins much of their ability to act as useful solvents, but its description is complicated by the long-ranged nature of dipolar interactions. This is particularly pronounced under the periodic boundary conditions commonly used in molecular simulations. In this article, the dielectric properties of a water model whose intermolecular electrostatic interactions are entirely short-ranged are investigated. This is done within the framework of local molecular-field theory (LMFT), which provides a well-controlled mean-field treatment of long-ranged electrostatics. This short-ranged model gives a remarkably good performance on a number of counts, and its apparent shortcomings are readily accounted for. These results not only lend support to LMFT as an approach for understanding solvation behavior, but also are relevant to those developing interaction potentials based on local descriptions of liquid structure.