  Ionic Coulomb blockade in nanopores is a phenomenon that shares some
similarities but also differences with its electronic counterpart. Here, we
investigate extensively this phenomenon using all-atom molecular dynamics of
ionic transport through nanopores of about one nanometer in diameter and up to
several nanometers in length. Our goal is to better understand the role of
atomic roughness and structure of the pore walls in the ionic Coulomb blockade.
Our numerical results reveal the following general trends. First, the nanopore
selectivity changes with its diameter, and the nanopore position in the
membrane influences the current strength. Second, the ionic transport through
the nanopore takes place in a hopping-like fashion over a set of discretized
states caused by local electric fields due to membrane atoms. In some cases,
this creates a slow-varying "crystal-like" structure of ions inside the
nanopore. Third, while at a given voltage, the resistance of the nanopore
depends on its length, the slope of this dependence appears to be independent
of the molarity of ions. An effective kinetic model that captures the ionic
Coulomb blockade behavior observed in MD simulations is formulated.
