Oriented nonspherical atoms in crystals deduced from X-ray scattering data

A crystallographic pro-molecule/pro-crystal model is described that goes be yond the standard reference model, which explicitly contains only numerical ly determined atomic positions and thermal vibrational smearings, while lea ving all other information lumped together in a so-called deformation densi ty. The new model includes further explicit parameters that identify valenc e-orbital orientations and occupancies of degenerate or near-degenerate ato mic ground states in crystals. A method is described for extracting this ad ditional information as well from X-ray data by least-mean-squares refineme nts. It is applied to the experimental data sets of three organic molecules : 9-(tert-butyl)anthracene, tetrafluoroterephthalonitrile, and 1,2,3-triazi ne. The electronic structure inferences are discussed.