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Presents the 2003 Executive Committee Report on meetings of the International Union of Crystallography. World Directory of Crystalography; List of publications; Work of the Commissions.

The problem of coincidences of planar lattices is analyzed using Clifford algebra. It is shown that an arbitrary coincidence isometry can be decomposed as a product of coincidence reflections and this allows planar coincidence lattices to be characterized algebraically. The cases of square, rectangular and rhombic lattices are worked out in detail. One of the aims of this work is to show the potential usefulness of Clifford algebra in crystallography. The power of Clifford algebra for expressing geometric ideas is exploited here and the procedure presented can be generalized to higher dimensions. [ABSTRACT FROM AUTHOR]

Discusses the charge density (CD) of a chemical compound, the most information-rich observable that is available for the system Information contained in the CE on the chemical bonding as well as on physical and chemical properties; Diffraction experiments at short wavelength and low temperature; Capability of CD to define the electronic ground state of a system.