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Manuscript Title: A program for the calculation of X-ray reflection intensities.
Authors: I.F. Ferguson, J.E. Kirwan
Program title: FIREFLY II
Catalogue identifier: AAQB_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 5(1973)328
Programming language: Fortran.
Computer: ICL 4-70.
Operating system: 7J.
RAM: 138K words
Word size: 8
Peripherals: magnetic tape.
Keywords: Crystallography, Intensities, X-ray, Powder, Diffraction, Structure-factor, Crystal-structure.
Classification: 8.

Nature of problem:
The program, FIREFLY II, calculates the intensities of X-ray reflections with special reference to the powder method. The program is very flexible and allows the intensity of reflections with given Miller indices to be calculated if the unit cell and its contents are specified together with the equipment used and, if necessary, temperature and absorption factors. Provision is made for the comparison of observed and calculated data.

Solution method:
The Bragg reflection is calculated by the standard formulae of X-ray diffraction as applied to X-ray powder diffraction.

Restrictions:
The program can manipulate up to 100 sets of Miller indices, 2000 atoms with coordinates xn, yn and zn, not greater than 100 atom types, 10 wave lengths and up to 1000 observed intensities and angles.

Running time:
5 s for a typical example.