Accurate calculation of long-range electrostatic interaction is not an easy task in molecular simulation. Though the rigorous Ewald method based on the reciprocal space has been established, real-space treatments have recently become an attractive alternative; the development is not yet completed and is now a challenging subject. In 1980, Neumann and Steinhauser employed the Onsager dielectric continuum model to explain how simple real-space cutoff produces artificial dipolar orientation. In the present study, we employ this continuum model to explore the fundamental properties of the recently developed real-space treatments of three shifting schemes. The result of the distance-dependent Kirkwood function GK(R) showed that the simple bare cutoff produces a well-known hole-shape artifact, whereas the shift treatments can remove it. Detailed view of electric field well explained how these shift treatments remove the hole-shape artifact. Yet, the shift treatments are not sufficient because they do not produce a flat GK(R) profile unlike ideal no-cutoff treatment. This result implies that not only shifting but also damping is required to obtain a more reliable result, as Wolf real-space treatment suggests.

Real-space electrostatic calculations in molecular simulation: dielectric continuum examination

ACS Spring 2022

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