No abstract

Abstract. Given a two dimensional oriented surface equipped with a simplicial mesh, the standard lowest order finite element spaces provide a complex X • centered on Raviart-Thomas divergence conforming vector fields. It can be seen as a realization of the simplicial cochain complex. We construct a new complex Y • of finite element spaces on the barycentric refinement of the mesh which can be seen as a realization of the simplicial chain complex on the original (unrefined) mesh, such that the L 2 duality is non-degenerate on Y i × X 2−i for each i ∈ {0, 1, 2}. In particular Y 1 is a space of curl-conforming vector fields which is L 2 dual to Raviart-Thomas div-conforming elements. When interpreted in terms of differential forms, these two complexes provide a finite-dimensional analogue of Hodge duality.

We use the integral equation approach to study electromagnetic scattering by perfectly conducting (non-orientable) Lipschitz screens. The well-posedness of the electric field integral equation is derived. The Galerkin method for this problem is analysed in a general setting and optimal error bounds are proved for conforming finite elements in natural norms.