on crystal, a major TRP image/metaphor. NOT naturally symmetrical!

[Mark Kohut]

http://www.newscientist.com/article/mg20427301.200-solving-the-crystal-maze-the-secrets-of-structure.html

Pickard chose to tackle carbon, an element that typifies crystal mystery: depending on how its atoms team up, it can form ultrahard transparent diamond, or soft grey graphite. He started off by tossing carbon atoms randomly into a box large enough to fit the basic "unit cell" of the crystal, and worked out the energy of the resulting structure. Knowing that nature always favours the lowest-energy arrangement, CASTEP could work out how the atoms could move to reduce their energy. By repeating this process until the energy could be reduced no more, the final structure should by rights be nature's crystal.

In fact, it was an almighty mess. The carbon atoms did not arrange themselves into the regular tetrahedral cage of a diamond crystal, or into the flat, honeycomb sheets that make up graphite. The structure had no obvious symmetry to it at all.