CrystalDiffract is a program to generate, display and manipulate x-ray powder diffraction patterns. CrystalDiffract is designed as a stand-alone program - but you will require the CrystalMaker program if you wish to generate crystals and diffraction patterns which are not included with the standard package. (See the help section "Ordering CrystalMaker" for more details).
The version of CrystalDiffract supplied here is a "FAT Binary" application. That is, it contains native PowerPC code, as well as regular "680x0" ("68K") code. This means that you can run the CrystalDiffract program on a PowerMac, or a regular Mac.
If you choose to use this version of CrystalDiffract on a regular Mac you must have a Maths coprocessor (FPU chip) installed.
CrystalDiffract requires around 2 MB of RAM free — though the exact amount depends on the number, and size of your graphics windows. You must be running MacOS version 7.0, or later. Your machine must have an mc68020 processor, or higher — or a PowerPC chip.
Getting Started with CrystalDiffract
Displaying A Diffraction Pattern
To generate and display a diffraction pattern, you must first open a Crystal file using CrystalDiffract. Either:
• In the Finder, drag a Crystal file icon onto the CrystalDiffract application icon
or/
• Launch CrystalDiffract, and select the Open command from the File menu, then choose a Crystal file to be opened.
If CrystalDiffract is able to read the Crystal file correctly, a graphics window will open, a diffraction pattern will be generated (this might take some time for non-PowerPC machines), and the results will be plotted.
Note that CrystalDiffract allows you to open multiple windows.
The ASF.dat file
The amplitude of x-ray radiation scattered by a single atom is defined by the atomic scattering factor (ASF). Its angular dependence is summarized in a 9-coefficient polynomial equation. The coefficients for the more common elements are located in the "ASF.dat" file - and you can add more element data if you wish.
CrystalDiffract attempts to open "ASF.dat" when it is first launched. If you do not supply an ASF.dat file, the program will use default coefficients (equating all atoms to Silicon).
Values for the ASF coefficients may be found in the International Tables for Crystallography, or in: Doyle & Turner (1968) Acta Crystallographica A24:390–397.
More Information about CrystalDiffract
CrystalDiffract has an on-line help window, which may be accessed by selected the "CrystalDiffract Help" command from the Help menu (the "?" icon at the right-hand side of the menu bar). There are two sets of help topics available: a general help topics list, and a second "How do I…?" list - you can select which list to display using the pop-up menu in the help window.
About CrystalMaker…
Interactive Crystallography for Macintosh and Power Macintosh
CrystalMaker is a program for displaying all kinds of crystal structures in stunning, photorealistic colour.
• Build Crystals Fast! Defining a crystal is very simple and requires the minimum of information. Ball-and-stick, space-filling, wire-frame, and polyhedral models are immediately available, and can be extensively customized.
• Real-Time Rotation - just click & drag with the mouse!
• Photo-realistic Displays: full rendering, with depth-cueing available.
• Flexible Plot Modes: Additional plot modes for diagrams in journals or lecture handouts - variety of polyhedral shaded fill-patterns and atom & bond styles.
• Interactive bond searching - investigate local environments
• Toolbars - lasso tool; info tool; rotate tool; scroll tool; measure bond distances & angles on screen; zap atoms tool
• Export text and graphics files
• Import text, STRUPLO and MacMolecule files
• High-quality printing
• User-friendly - exclusively Macintosh.
• Crystal structures library - over 220 structures. Ideal for teaching and research.
• 160-page manual
CrystalMaker is a low-cost, high-value software package. We give very generous academic discounts, and our 10- and 20-user group licences are amazing value.
CrystalMaker is marketed by:-
LYNXVALE LTD., 20 Trumpington Street. Cambridge, CB2 1QA. England
Tel.: +44 (1223) 334755 • Fax.: +44 (1223) 332797
E-mail: sjm21@cus.cam.ac.uk
For technical details, send e-mail to: D.C.Palmer@eWorld.com
Why not try out a demo version of CrystalMaker? You can download one by anonymous ftp from:-
