Nonequilibrium Linear Response Theory: Application to Onsager–Stefan–Maxwell Diffusion

The original regression hypothesis of Onsager contains more physics than the fluctuation–dissipation theorem. A discrepancy in a prior derivation of the reciprocal relation for Stefan–Maxwell coefficients through fluctuation theory is resolved. Along with a demonstration of the correct reciprocal relation, it is shown how to use the regression hypothesis to analyze data from an equilibrium simulation and determine values of the transport coefficients.