'CrystalMaker'

Mac loving crystallographers with a fast graphics card and good eyesight will love 'CrystalMaker', written by David Palmer, of the Earth Sciences Department Cambridge, UK, primarily as a visualisation tool for first year crystallography students in their Department. It will also be useful for research workers since it displays structures so well; it does not attempt to teach. (If you want a teaching program try the Geology TLTP module 'Crystallography' which runs on both Macs and Pcs. I hope to review it in a later issue) 'CrystalMaker' is a very 'user-friendly' way for students to explore various models of the atoms and bonds inside crystals, but not their external morphology. 150 data files are supplied for students to explore the crystal classes, and many general substances. However, if they are not to just waste time admiring the pretty pictures, the teacher will need to produce a set of worksheets to guide the explorations. A set of these on disc, or as easily copied pages from the user manual would make a useful addition.

Installation and testing: 'Crystalmaker' is supplied in 3 versions, each optimised to run on different types of Mac. With the help of friends in Oxford and at RAL I tried all three, on a Mac II with 8Mb Ram a 14" colour screen and a fairly full 80Mb hard disc, a Mac IIci with a monochrome A3 size screen normally used for word processing, and a PowerPC Model (9500/132) with 17" colour screen. Installation was easy on the smaller models, and easy on the bigger one after we read the 'Installation instructions' again, looked at the 'readme' file supplied, and realised that the Mac utility 'QuickTime' must be installed, so that the 'CrystalMaker' movie option can be used later. This option makes a convenient way to set up a sequence of operations illustrating points made during a lecture. An example 'movie' is provided on the disc. The program follows the usual Mac windows and pull down menus conventions. In addition it has the less usual 'toolbar' icons and information written into the lower 'window frame'.These give very easy access to on screen operations if you can see them; we all found them too small for easy legibility, even on the large high resolution screen. Modelling options provided are stick, ball and stick, spacefilling and polyhedral modes.The figure also shows the 'lasso' operation, where you restrict the drawing to part of the structure by encircling the atoms you want by drawing round them with the mouse pointer. Atom parameters such as radius and colour are read from a default file but can be changed interactively. Bonds, atoms and polyhedra can be displayed in various ways, the selection is laid out for you in a window and you merely click your mouse pointer over the one you want to use. Entering a new crystal is easy, we had no trouble following the 'tutorial' in the manual. You can ask to replicate the atoms over larger volumes, by specifying the minimum and maximum distances to see in Angstroms. The x,y,z directions are treated independently, so you have 6 real numbers to type. This gives great flexibility, but I found it irritating when all I wanted was a whole number of unit cell replications, and I thought one number should have been sufficient. The program helpfully tells you how many unit cells your space covers and how many atoms will be in the resulting diagram, so that you can change your mind and ask for a smaller range if you are using a small computer.

We found interactive rotation of the structure with the mouse was a joy on the PowerPc mac and impossibly slow on the other models when we had more than a few atoms on the screen. A status window helpfully tells you what the program is doing while you are waiting, and shows you a moving bar slowly filling an icon; I would not want to use this program on macs without fast graphics cards.

File formats:' CrystalMaker' reads only external files in the format of 'STRUPLO' or 'MacMolecule'. (Mac Molecule is freely available over the InterNet from the University of Arizona by ftp from joplin.biosci.arozina.edu). It would be much more useful if it could handle CIF files, or those from the large databases, CCDC, ICSD etc. It can save files in its own format, which stores the plotting parameters last used with the atom and bond positions, and subsequently loads much more quickly.

Hardcopy is via the Mac utilities. Pictures may be saved to files as bitmaps in 'PICT' or in vectors in 'QuickDraw' formats or to the Mac 'clipboard' for import into word processing packages. Elegantly rendered coloured shaded models can be printed, or grey scale ones for publication. A 'print preview' options allows plot inspection before printing. I found the high resolution plots took a very long time to print, possibly because the Mac was connected to a public printer served from a network. The lower resolution plots printed with acceptable speed and quality for most purposes.

Conclusion: Very good value for money if you have a Mac with a large screen and a fast graphics card and you want a 'user friendly' package for exploring crystal structures, with an option to make demonstration movies. It is very much easier to use than the older mac program, 'Atoms', from 'Shape Software', but I would not throw away 'Atoms' yet because it can read files in the formats from some of the large databases, draw atoms as thermal ellipsoids (ORTEP like) and export pictures in PostScript format. This means not only will they print more quickly over a network, but you can take your file to a printing bureau with very high resolution PostScript printers and produce a much better quality print for your Conference poster Annual Report or presentation to funding bodies.

Further information: can be found on the WWW, most easily via a link from the BCA software pages to the URL where you can read another review, find out how to get a free 'Demo' version of both 'CrystalMaker' and the associated program 'CrystalDiffract' which generates, displays and manipulates x-ray powder diffraction patterns from the current structure in 'CrystalMaker'. [email protected] Click here to return to BCA homepage