Ewald summation for systems with slab geometry

TLDR

The authors propose a modification to the three‑dimensional Ewald summation that enables accurate long‑range Coulombic force calculations for slab‑geometry systems periodic in two dimensions and finite in the third. The modification adds a correction term to the standard Ewald formula and is validated through molecular‑dynamics simulations of water confined between Pt(111) walls and by computing pair forces between two point charges. The approach yields excellent agreement with rigorous two‑dimensional Ewald results while significantly reducing computational time.

Abstract

We propose a modification in the three-dimensional Ewald summation technique for calculations of long-range Coulombic forces for systems with a slab geometry that are periodic in two dimensions and have a finite length in the third dimension. The proposed method adds a correction term to the standard Ewald summation formula. To test the current method, molecular dynamics simulations on water between Pt(111) walls have been carried out. For a more direct test, the calculation of the pair forces between two point charges has been also performed. An excellent agreement with the results from simulations using the rigorous two dimensional Ewald summation technique were obtained. We observed that a significant reduction in computing time can be achieved when the proposed modification is used.