Charge deformation maps, molecular moments, and high-energy electron scattering

We review the progress which was made during the last 6 years in the attempts to use electron diffraction data to gain insights into the electronic charge densities of isolated molecules and their moments. In regard to theory, we investigated the sensitivity of the elastic differential high-energy cross sections to the basis sets in the wave function calculations. Extensive calculations on H2O showed that there is no significant change by the molecular vibrations on the static charge density deformation maps. Finally new relations could be derived which allow the determination of nuclear and electronic moments from the differential cross sections at small angles. In regard to experimental data, new sets of purely elastic cross sections are available for He, Ne, CO2, N2, and CH4, which are compared with Hartree-Fock and limited configuration interaction wave function results. The differences are discussed. New experimental values for some moments for N2 and CH4 are reported.