The XD Package. T. Richter, T. Koritsanszky, S. Howard, P.R. Mallinson, Z. Su and N.K. Hansen, Institute for Crystallography, Free University of Berlin, Germany

XD is a computer program package for multipole refinement and analysis of electron densities from diffraction data. It has been developed within an IUCr project by an international programming team. The main task of the package is to extract electronic properties from Bragg reflections and to perform topological analysis on 3D properties such as the electron density, its Laplacian function /1/ or the electrostatic potential. The program consists of the following programs (among others):

* xdini - convert data from conventional refinement packages

* xdlsm - least-squares program

* xdfour - general plane Fourier program

* xdprop - electronic properties, topological analysis

* xdgeom - geometrical analysis

* xdstat - statistical analysis

* xdgraph - graphical output

After an introduction to the package in general and some of the individual programs, a hands-on tutorial session using computer workstations will be held.

/1/ R.F.W. Bader, Atoms in Molecules: A Quantum Theory, Oxford University Press (1990)