- For more information on both types of twinning the please see the Introduction to Hemihedral Twinning
- Perfect Merohedral Twinning Test
- Perfect Merohedral Twinning involves a crystal with a twin fraction equal to or near 1/2. This test will attempt to determine the presence of twinning by comparing the diffraction data to that expected by Wilson statistics.
- Partial Merohedral Twinning Test
- Partial Merohedral Twinning involves twinning with a twin fraction not equal to 1/2. This test will attempt to estimate the twin fraction alpha statistically.
Å - Å
- Output Format (Perfect Twinning Test Only)
- The Perfect Merohedral Twinning Test partitions reflection data by resolution and performs independent calculations on the individual shells. The results may therefore be output in graphical (Postscript) format, or in plain text.
- Reflection Discard Fraction (Partial Twinning Test Only)
- The Partial Merohedral Twinning Test utilizes a statistical comparison of twin-law-related reflection pairs. Without loss of validity, the specified percentage of these pairs are discarded based upon the sum of their intensities in order to minimize statistical error.
|Please select a data file to upload: |
- Data File Format
- The XPLOR format assumes records of the following form:
INDEX 0 1 -13 FOBS 285.27
INDEX 0 1 -10 FOBS 495.87
INDEX 0 1 -7 FOBS 306.33
INDEX 0 1 -4 FOBS 375.55
Only accepts XPLOR format
|Unit Cell Dimensions|
( a , b , c ) = (
Å ) |
( alpha , beta , gamma ) = (
|Apparent Space Group|
|Please verify all your settings and click the submission button below to upload your data file and perform the twinning test. Depending on your internet connection, abnormally large data files may cause a delay in upload time. The test itself normally does not take more than a few seconds. If you have selected Postscript output you may need to save the results to disk and open this file with an external viewing program.
The server requires only a few seconds to return a result. If your submission takes minutes or does not return, or you get an error message of any kind, please feel free to contact the administrator