Self-diffusion in one-dimensional lattice gases in the presence of an external field (Q578760)

We study the motion of a tagged particle in a one-dimensional lattice gas with nearest-neighbor asymmetric jumps, with p (respectively q), \(p>q\), the probability to jump to the right (left). It was shown that the fluctuations in the position of the tagged particle behave normally: \(<(\Delta X)^ 2>\sim Dt\). Here we compute explicitly the diffusion coefficient. We find \(D=(1-\rho)(p-q)\), where \(\rho\) is the gas density. The result confirms some recent conjectures based on theoretical arguments and computer experiments.