Continuum vs. particle simulations of model nano-pores

The class of biological macromolecules known as ion channels are becoming of great interest to physical scientists and engineers, as well as biophysicists and pharmacologists. The long term stability and wide range of properties displayed by this large group of proteins makes them one of the most popular contenders to bridge the gap between solid state electronics and biological systems. However, many of the most basic mechanisms by which these molecules conduct ions are still poorly understood. We present a comparison between the behaviour of continuum and discrete particle methods in simulations of sub-nanometre diameter model pores. Using Drift Diffusion and Self Consistent Brownian dynamics simulations we demonstrate that, without serious modification, continuum methods are insufficient to model even simple pores of these dimensions.