`Yablonovite' is made by covering a slab of material with a mask
consisting of a triangular array of holes. Then, each hole is drilled through
three times at an angle of 35.26 from the normal and spread out 120 degrees on
the azimuth. This forms a network of intersecting holes below the surface with
an FCC structure. (See the figure above)
In order the produce a crystal which has a band gap at optical wavelengths it
is necessary to scale the production process down to a micron length scale.
This has, however, proven to be technically challenging. Finding the
equivalent of a drill bit with a micron diameter is far from straightforward!
This has motivated a search for other structures which are more easily
fabricated. One possibility is the Logpile structure, the simple cubic
version of which is shown in the second figure. This has proved to be a very
useful trial system on which we can test many of our ideas and computational