TEACHING DIFFRACTION WITH THE AID OF COMPUTER-SIMULATIONS

A high degree of motivation and very effective learning can be achieve d by the combination of multimedia presentations with computer simulat ions of structures and their corresponding Fourier transforms. Compute r simulations of structures offer the unique advantage that students s ee both the structure and the resulting Fourier transform. Furthermore , since any type of structure can be simulated, a systematic approach to diffraction can be taught with maximum efficiency. The students can simulate their own structures, modify these and observe the correspon ding changes in reciprocal space. In the course reported here, student s are guided through a series of simulations covering diffraction by i ndividual atoms and small aggregates, reciprocal-space geometry, convo lution, modification of a structure, the crystallographic phase proble m, inverse Fourier transformation, anomalous scattering, powder diffra ction and disordered crystals. The course is supplemented by World Wid e Web pages that guide self study and prompt the students to try out t heir own simulations and observe the effect in reciprocal space.