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[Licence| Download | New Version Template] abmt_v1_0.gz(8 Kbytes)
Manuscript Title: A simple FORTRAN program to interpret cubic X-ray powder diffraction data.
Authors: E.D. von Meerwall
Program title: XRAY2
Catalogue identifier: ABMT_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 11(1976)331
Programming language: Fortran.
Computer: IBM 370/158.
Operating system: OS/MVT, OS/VS2.
RAM: 8K words
Word size: 32
Keywords: Crystallography, Diffraction, Powder method, Debye-scherrer, Indexing, X-ray, Cubic lattice, Orthorhombic, Tetragonal, Lattice parameter fit.
Classification: 8.

Nature of problem:
Powder X-ray diffraction data can be tested for the presence and approximate amount of cubic, tetragonal, or orthorhombic lattices whose dimensions are known approximately. For cubic types, a careful determination of the lattice parameter is made.

Solution method:
The Bragg equation with given parameters is inverted to give primitive plane spacings, which are then associated with the nearest (if acceptable) observed lines by indices and order. For cubic types, a Taylor-Sinclair extrapolation of the lattice parameter is made, based on the identified lines.

Restrictions:
The present limit of 50 observed lines is easily removed by redimension- ing and altering one loop parameter.

Unusual features:
The program is intended as an aid in identifying powder diffraction patterns, and to make precision measurements of cubic lattice parameters. (1) Line positions are accepted either as angles theta or as cm readings on film; in the latter case, the theta = 0 position (and film shrinkage) may be found by the program and (2) several hypothetical structures per spectrum may be tested for; line intensities are not used in the identification, but only to estimate relative identified intensity.

Running time:
On the IBM 370/158, the program compiles (G level) in about 3 CPU s. A typical case with 15 lines, a limit on reflection indices of six, and two hypotheses, takes about 1 s CPU time.