An Interior Penalty Method with $C^0$ Finite Elements for the   Approximation of the Maxwell Equations in Heterogeneous Media: Convergence   Analysis with Minimal Regularity
  The present paper proposes and analyzes an interior penalty technique using $C^0$-finite elements to solve the Maxwell equations in domains with heterogeneous properties. The convergence analysis for the boundary value problem and the eigenvalue problem is done assuming only minimal regularity in Lipschitz domains. The method is shown to converge for any polynomial degrees and to be spectrally correct. 
Andrea Bonito and Jean-Luc Guermond and Francky Luddens
math.NA