THEORY OF THE MEISSNER EFFECT

In order to obtain an explicitly gauge-invariant description of the Meissner effect in superconductors, Wentzel¹ has recently suggested an approach which differs in several essential respects from that developed by Bardeen, Cooper, and Schrieffer.² Wentzel finds in the long-wavelength limit a relation between the current density and the magnetic vector potential which differs from the London value given by the BCS theory. We wish to point out that this discrepancy is due to Wentzel's assumption that corrections to his approach possess a convergent expansion in powers of the phonon-electron coupling constant, g. It is our belief that this expansion does not exist…