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Macroscopic surface charges from microscopic simulations
1Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
The Journal of Chemical Physics
|November 3, 2020
Summary
Molecular simulations of charged surfaces require accurate ion density profiles. Imposing an electric displacement field (D) in slab simulations determines surface charge density, overcoming slab thickness limitations.
Area of Science:
- Computational chemistry
- Surface science
- Electrochemistry
Background:
- Accurate molecular simulation is crucial for understanding system behavior.
- Ion density profiles near charged surfaces are key for electrolyte solutions.
- Standard simulation methods may introduce artifacts in surface charge calculations.
Purpose of the Study:
- To develop a robust method for determining macroscopic surface charge densities in molecular simulations.
- To address limitations of existing methods like the Yeh-Berkowitz approach and mirrored slab geometry.
- To validate the proposed method on both simple and complex charged interfaces.
Main Methods:
- Molecular dynamics simulations in slab geometry.
- Application of an electric displacement field (D) to charged interfaces.
- Analysis of ion density profiles normal to the surface.
Main Results:
- Imposing an electric displacement field (D) accurately determines integrated surface charge density.
- This method yields macroscopic surface charge densities independent of slab thickness.
- The Yeh-Berkowitz method and mirrored slab geometry were shown to yield vanishing integrated surface charge densities.
Conclusions:
- The electric displacement field method provides a reliable way to calculate surface charge density in simulations.
- This approach overcomes artifacts associated with slab thickness and common simulation geometries.
- The findings are applicable to various charged interfaces, including mineral-water systems.
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