  In order to detect the effect of the surface charge discreteness on the
properties at the solid-liquid interface, molecular dynamics simulation model
taking consideration of the vibration of wall atoms was used to investigate the
ion and water performance under different charge distributions. Through the
comparison between simulation results and the theoretical prediction, it was
found that, with the degree of discreteness increasing, much more counterions
were attracted to the surface. These ions formed a denser accumulating layer
which located much nearer to the surface and caused charge inversion. The ions
in this layer were non-hydrated or partially hydrated. When a voltage was
applied across the nanochannel, this dense accumulating layer did not move
unlike the ions near uniformly charged surface. From the water density profiles
obtained in nanochannels with different surface charge distributions, the
influence of the surface charge discreteness on the water distributions could
be neglected.
