The outer membrane of Gram-negative bacteria serves as a protective barrier against the external environment but is rendered selectively permeable to nutrients and waste by proteins called porins. Other outer membrane proteins (OMPs) provide the membrane with a variety of other functions including active transport, catalysis, pathogenesis and signal transduction. A relatively small number of crystal or NMR structures of these proteins are known, and it is therefore essential that the maximum possible information be extracted. In this respect, computational techniques enable extrapolation from time- and space-averaged static structures to dynamic, physiological events. Electrostatics approaches have been used to investigate the structures of porins. The stochastic simulation of ion trajectories through these channels has been possible with Brownian dynamics, which treats the membrane and solvent approximately, enabling the prediction of conduction properties. Molecular dynamics has also been applied, enabl...