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Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. Simulations of nonneutral slab systems with longrange electrostatic interactions in twodimensional periodic boundary conditions
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Postprint urn:nbn:de:0011n1049900 (208 KByte PDF) MD5 Fingerprint: 4921d7827965df8e30b6963f00d022e4 Copyright AIP Erstellt am: 24.9.2009 
 The Journal of chemical physics 131 (2009), Nr.9, Art. 094107, 10 S. ISSN: 00219606 

 Englisch 
 Zeitschriftenaufsatz, Elektronische Publikation 
 Fraunhofer SCAI () 
 electrostatics; partially periodic boundary conditions 
Abstract
We introduce a regularization procedure to define electrostatic energies and forces in a slab system of thickness h that is periodic in two dimensions and carries a net charge. The regularization corresponds to a neutralization of the system by two charged walls and can be viewed as the extension to the twodimensional (2D)+h geometry of the neutralization by a homogeneous background in the standard threedimensional Ewald method. The energies and forces can be computed efficiently by using advanced methods for systems with 2D periodicity, such as MMM2D or P3M/ELC, or by introducing a simple backgroundcharge correction to the Yeh–Berkowitz approach of slab systems. The results are checked against direct lattice sum calculations on simple systems. We show, in particular, that the Madelung energy of a 2D square charge lattice in a uniform compensating background is correctly reproduced to high accuracy. A molecular dynamics simulation of a sodium ion close to an air/water interface is performed to demonstrate that the method does indeed provide consistent longrange electrostatics. The mean force on the ion reduces at large distances to the imagecharge interaction predicted by macroscopic electrostatics. This result is used to determine precisely the position of the macroscopic dielectric interface with respect to the true molecular surface.