Bernoulli potential in superconductors

The Bernoulli potential in a superconductor is calculated using the Gorkov equations. General expressions for the potential are derived. In the high-kappa limit, the expression reduces to the result of the two-fluid model augmented by a term due to the spatial variation of the order parameter. The temperature dependence of the potential is computed, in the case of clean superconductors, for various values of kappa, and, in the case of impure superconductors, for kappa=infinity