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Beartex-MIMA

Evaluates Orientation Space Coverage from Pole Figures

MIMA evaluates the OD coverage of the orientation space. Input are the extents of experimental pole figures hkl and crystal symmetry, outputs are the numbers of pole figure projection paths intersecting in the corresponding 5x5x5 degree OD cell. In order to simply define an orientation the minimum number of intersections must be 3. For OD determination more than 3, preferably 10 or more are recommended. The file mima.pro contains this information, that you can open with the FILE Beartex menu. It is useful to run this program with potential pole figures before diffraction experiments and before the OD calculation. It is assumed that data have been measured in full azimuthal rings. In this case a representation of the determinacy that depends on two Euler angles is sufficient. The third angle is redundant. The results possess symmetry properties like an inverse pole figure (For details see Helming, 1991).

Crystal symmetry codes for the 11 rotation groups are given below (they are on data and .cfg files). For sample symmetries choose among 222 (3), 2 (2) and 1 (1).

System	cubic	tetrag.	ort.	mon.	tric.	hexag.	trigon.
Point group	O	T	D4	C4	D2	C2	C1	D6	C6	D3	C3
		432	23	422	4	222	2	1	622	6	32	3
Code igb	7	6	5	4	3	2	1	11	10	9	8

In MIMA there is an optional input file. Default file is C:\BEARTEX\DEMO.XPE. This is usually an experimental data file of which you want to determine if it provides complete OD coverage.

Alternatively you may change crystal symmetry (sample symmetry is always 1) and lattice parameters. Then select a series of pole figures (hkl) and corresponding minimal and maximal pole distances.

Exemples:

Cubic crystal system with 3 experimental pole figures analyzed up to a pole distance of 45 degrees.
Tetragonal crystal system, HgI₂, alpha form.