Simulations of electroosmotic flow in charged nanopores using Dissipative Particle Dynamics with Ewald summation

Abstract

We present a Dissipative Particle Dynamics simulation method that allows us to study electroosmotic flows inside cylindrical nanopores with uniform surface charge. To properly treat the long-range electrostatic interactions between all the charges, we use two different approaches. In the first approach, the uniform surface charge is represented using surface point sites. The Coulomb interaction is then treated using 3d Ewald summation with an appropriate correction for the pseudo 1d geometry. In the second approach, the surface charge is treated implicitly. It produces an external potential in which all other particles move. In the case of an infinite cylinder, the electric field produced by a uniform surface charge vanishes. However, the rest of the system is no longer charge neutral. This requires an additional correction to the Ewald summation method. Since the second method does not use the explicit surface charges, it is about 40% more efficient – while producing identical electroosmotic flow and ionic charge distribution inside the pore.