E0044

Crystallographic Education: MATLAB as a Tool in Teaching X-Ray Crystallography. Maureen M. Julian, Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA, 24060 USA, erie@vt.edu.

My x-ray crystallography course has been greatly changed by the introduction of MATLAB. Calculations are now practical which previously were only presented conceptually or were clumsy in Excel. Two crystal structures are chosen to illustrate a wide range of crystallographic features: 1) Hexamethylbenzene is triclinic and centrosymmetric with one molecule to the unit cell. This is the students’ introduction to non-orthogonality. 2) Anhydrous alum, KAl(SO₄)₂, is a non-centrosymmetric framework structure with trigonal symmetry. Two types of crystallographically distinct oxygens are present.

Three-dimensional plots in MATLAB show the unit cell, the asymmetric unit, the reciprocal cell, and the complete structure with the atoms and connecting bonds for the two structures mentioned above and for the each student’s own structure selected from the crystallographic literature. Other MATLAB calculations include the x-ray diffraction powder patterns, the metric matrix, point group multiplication tables, atomic scattering curves, structure factor calculations, a Moseley plot, and electron density maps. Each student presents his or her own crystal in our annual ‘Festival of Crystals’. Samples of the student reports are available.