PROGRAM SUMMARY
Title of program:
QCDiffractor
Catalogue identifier:
ADNU
Ref. in CPC:
136(2001)236
Distribution format: gzip file
Number of lines in distributed program, including test data, etc:
121
Keywords:
H2 quasicrystals, Quasicrystal diffraction, Mathematica, QCDiffractor,
Crystallography.
Programming language used: Mathematica
Nature of problem:
Generation of quasicrystal images and their X-ray diffraction patterns.
Method of solution:
The desired quasicrystal fragment is obtained and drawn using a "cut and
project scheme". Each point (atom) of the quasicrystal fragment is
replaced by a delta function such that its "spike" has the same
coordinates as the corresponding quasicrystal point; the (finite) sum of
all such delta functions is taken, and the Fourier transform of the sum
is then calculated; taking the square of the modulus of the
abovementioned Fourier transform yields the diffraction intensity in the
case of a perfectly sensitive detector. One may plot this intensity if
one chooses, or introduce a threshold intensity (below which detection
is impossible) in order to model an imperfectly sensitive detector.
Restrictions:
The time and memory required increase when one augments the resolution
of the diffraction image or the number of points in the fragment. The
number of points in the fragment is roughly proportional to the area of
the fragment region as well as to the area of the window region.
Typical running time:
Several minutes for simple examples; hours or days for more complex
cases.
Unusual features:
A threshold diffraction intensity for detection has been incorporated
into the program.