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[ Identification | Description | Input parameters | Output parameters | Links ]
The Laue_crystal_BC Component
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* Perfect, laue crystal with common cubic structures (diamond, fcc, or bcc, and others if symmetry form factor multipliers provided explicitly)
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Identification
- Site:
- Author: Marcus H Mendenhall, NIST
- Origin: Marcus H. Mendenhall, NIST, Gaithersburg, MD, USA
- Date: June, 2017
Description
* NIST_Laue_crystal_BC.comp is written by Marcus H. Mendenhall, NIST, Gaithersburg, MD, USA * It is based on the full vector math and exact solution of the dispersion relation in * Batterman and Cole, Reviews of Modern Physics 36 number 3, page 681, July 1964 * Non-copyright notice: * Contributed by the National Institute of Standards and Technology; not subject to copyright in the United States. * This is not an official contribution, in that the results are in no way certified by NIST. * Perfect crystal with common cubic structures (diamond, fcc, or bcc, and others if symmetry form factor multipliers provided explicitly) * * Reads atomic form factors from a data input file. * The Laue_Crystal code reflects rays in an ideal geometry, does not include surface imperfections or mosaicity. * * The crystal is positioned such that the long axis of the crystal surface coincides with * z-axis and the outer normal to the crystal surface is along +y. * * The ratio of the transmitted beam and forward-diffracted Borrman-effect beam is a hack. The sum of the * two is exactly right, but the actual ratio depends critically on geometry, and I just put in a wild estimate * to allow one to demonstrate what the Borrmann effect looks like. If this is turned on, the displacement of the * transmitted beam and forward diffracted beam at the back side of the crystal will be correctly computed. * This displacement is only exact for symmetrical Laue; asymmetrical computation requires more effort, * and is probably not worth it. * The sampling of these processes are controlled by the 3 variables transmission_sampling, forward_diffraction_sampling, * and laue_sampling. Since 99% of uses of this will have the transmitted beam turned off, and use laue diffraction mode, * the values should be just 0,0,1. If the general behavior of the transmitted beams * is interesting, use 1,1,1 which samples all beams equally. Results weights are adjusted for this, * so computed intensities won't be affected. * * * *
Input parameters
Parameters in boldface are required; the others are optional.| Name | Unit | Description | Default |
| length | 0.05 | ||
| width | 0.02 | ||
| thickness | 1e-4 | ||
| V | 160.1826 | ||
| form_factors | "FormFactors.txt" | ||
| material | "Si.txt" | ||
| alphax | 0.0 | ||
| alphay | 0.0 | ||
| alphaz | 1.0 | ||
| debye_waller_B | 0.4632 | ||
| crystal_type | 1 | ||
| h | 1 | ||
| k | 1 | ||
| l | 1 | ||
| structure_factor_scale_r | 0.0 | ||
| structure_factor_scale_i | 0.0 | ||
| transmission_sampling | 1.0 | ||
| forward_diffraction_sampling | 1.0 | ||
| laue_sampling | 1.0 |
Output parameters
Parameters in boldface are required; the others are optional.| Name | Unit | Description | Default |
| prms |
Links
- Source code for
Laue_crystal_BC.comp.
[ Identification | Description | Input parameters | Output parameters | Links ]
Generated on 2022-02-07 21:31:39
