W0154

Online Tutorials - A Tool to Teach Crystallography. Peter Müller, UCLA Center for Genomics and Proteomics, 205 Boyer Hall, Box 951570, Los Angeles, CA 90095-1570, peterm@mbi.ucla.edu

Crystallography has become increasingly important in the last few decades as the method of choice when it comes to structure determination. Teaching crystallography, however, does not seem to be as fashionable as the method itself, and many people doing the job of a crystallographer lack basic knowledge about the method they use. The importance of teaching crystallography is generally acknowledged, but the time to teach and to be taught is frequently limited.

Online tutorials can provide access to knowledge and skills in a very flexible way, and can help to understand complex topics such as twinning or disorder. Kevin Cowtan’s legendary page featuring the Fourier duck and the Fourier cat [1], for example, has proven to be extremely instructive. Hundreds of young and even older scientists have learned a lot about the phase problem and model-bias, etc.

This presentation deals with an online tutorial about disorder. It can be found under the following URL:

http://shelx.uni-ac.gwdg.de/~peterm/tutorial/disord.htm

On several pages the user gets a brief or - if he or she should wish - a more detailed description of what disorder is and what the refinement of disordered structures can and should take into account (e.g. the use of restraints, etc.). The practical part that follows gives examples and is oriented on the refinement using the program SHELXL [2].

The user may download the .ins and .hkl files for each example and perform his or her own refinement. Each step, from the appearance of the problem to the final .res file, is explained and illustrated (mostly with animated .gif pictures), and all .ins and .res files are provided for download.

This simulates a real hands-on session as held at several workshops: The student gets an introduction and a problem and can try to solve it, either autonomously or with the assistance of a teacher. The only difference is the physical absence of the teacher, which makes it difficult for the student to ask questions. However, the e-mail address of the author is given, and several people have already made use of it.

[1] http://www.yorvic.york.ac.uk/~cowtan/fourier/fourier.html

[2] G. M. Sheldrick, SHELXL, Universität Göttingen, 1997.