Test of rate theory transmission coefficient algorithms. An application to ion channels

The determination of rate constants is an important problem in many areas of chemical physics. Transition state theory (TST) is often used in estimating the rate constants. However TST neglects recrossings of the transition state by the reaction coordinate. The transmission coefficient is a correction to the TST estimate which accounts for the influence of recrossing dynamics. The transmission coefficient is calculated by generating activated trajectories which cross the transition state. This article investigates the correctness and efficiency of several current numerical algorithms for estimating the transmission coefficient, as well as a new one presented here. We use these algorithms to estimate the transmission coefficient for K + diffusion through a model inward rectifier potassium (IRK1) ion channel.