Simulation of an ion channel. Biological membrane (grey) with an ion channel (centre) immersed in a solution of water and ions. This cross section of a simulation 'box' shows the electric potential, the externally supplied 'force' that drives ions through the channel. The pattern in this potential is due to the presence of the channel. The slowly decaying nature of this pattern makes simulations difficult, but use of the golden aspect ratio allows for small simulations to be used to study larger dimensions. This research was carried out at the Center for Nanoscale Science and Technology (CNST) of the National Institute of Standards and Technology (NIST). Image published in 2017.