A direct steady-state computer simulation method for calculating the Onsager phenomenological transport coefficient from the gradient of the chemical potential in the one component lattice gas was presented. It was shown that the results were in good agreement with the Einstein method. A recent alternative formulation for Fick's First Law that had been proposed to replace the standard Fick's First Law formulation was also analysed using the same model. It was shown that the alternative formulation gives poor agreement with the simulation data whereas the standard Fick's First Law gives excellent agreement. Accordingly, the alternative formulation did not appear to have merit as a new definition of the diffusion coefficient. It was shown that the alternative formulation was a rough approximation for the dependence of the interstitial solute diffusion coefficient on solute concentration in an interstitial solid solution if information about the activity coefficient and solute diffusion coefficient at very dilute concentrations was available. However, in this role, this was not an entirely new idea.

Computer Simulation of the Phenomenological Transport Coefficient in the Lattice Gas and Fick’s First Law. I.V.Belova, M.J.Brown, G.E.Murch: Philosophical Magazine, 2005, 85[14], 1495-506