Edge element computation of Maxwell's eigenvalues on general quadrilateral meshes

Recent results prove that Nedelec edge elements do not achieve optimal rate of approximation on general quadrilateral meshes. In particular, lowest order edge elements provide stable but non-convergent approximation of Maxwell's eigenvalues. In this paper we analyze a modification of standard edge element that restores the optimality of the convergence. This modification is based on a projection technique that can
be interpreted as a reduced integration procedure.