Programs in Physics & Physical Chemistry
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|Manuscript Title: Plot program for Laue patterns and stereographic projections.|
|Authors: E. Preuss|
|Program title: PLOMAC|
|Catalogue identifier: AAQE_v1_0|
Distribution format: gz
|Journal reference: Comput. Phys. Commun. 18(1979)261|
|Programming language: Fortran.|
|Computer: IBM 370/168.|
|Operating system: MVS.|
|RAM: 332K words|
|Word size: 8|
|Peripherals: magnetic tape, graph plotter.|
|Keywords: Crystallography, Crystal structure, Crystal diffraction, X-ray diffraction, Orientation of single Crystals, Single crystal surface Preparation, Gnomonic and Stereographic projection, Flat and cylindrical Laue photographs, Transmission and Back-reflection Laue techniques.|
Nature of problem:
The program simulates Laue patterns of any crystal type and of any crystal orientation. With the aid of a catalogue of plotted Laue diagrams the orientation of single crystals can be carried out quite easily by the direct comparison of the Laue photographs with the diagrams. This can be performed even by people with no previous experience in this field.
Trigonometric functions, vector algebra and formulas of analytic geometry are used. Transformation equations, relating the Miller indices of any crystal type with those in a rectangular Cartesian coordinate system, are introduced. The coordinates for the Laue spots are evaluated by the program. They are not read from cards or from a magnetic tape. The complete symmetry rather than the exact intensity of the plotted spots is essential for the crystal orientation method.
The structure factor and the crystal parameters of the unit cell must be known. There are ten structure factors for the most common crystal types in the program which can be called up ad-lib. These can be replaced by 17 structure factors for less common crystal types on comment cards or by others, if needed.
The software subprograms for the CALCOMP plots (California Computer Products, In.) CALCMP, NUMBR, SYMBL, FAKT, CALIN, FRAMAD, CALEND must be replaced if other plotters are used.
~~30 s for one diagram.
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