Topological methods for the prescribed Webster Scalar Curvature problem on CR manifolds

We consider the existence of contact forms of prescribed Webster scalar curvature on a (2n+1)(2n+1)-dimensional CR compact manifold locally conformally CR   equivalent to the standard unit sphere S2n+1S2n+1 of Cn+1Cn+1. We give some existence results, using dynamical and topological methods involving the study of the critical points at infinity of the associated noncompact variational problem.