Electron-densities for pseudo-relativistic atoms and molecules

We apply techniques developed earlier for the non-relativistic case to the case of 'pseudo-relativistic' atoms and molecules (the kinetic energi is given by the squareroot of p^2+m^2) to prove smoothness of the density away from nuclei. We also give a 'cusp' condition for the behaviour at the nucleus (in the atomic case), which differs from the non-relativistic case in an essential way. This is an ongoing collaboration with S.Fournais, CNRS, Laboratoire de Mathématiques, Université de Paris Sud, France.