The neighbour_list program only works with the old format of the supercell configuration. These days we almost always use the rmc6f format, but before this format, there was an old version of the configuration in the rmc3 format. The data2config program can be used to convert from rmc6f to rmc3 (with the extension of cfg). For the conversion, we basically want to generate a 1x1x1 'supercell' from the input rmc6f configuration, so nothing is really happening except from the format conversion.

The neighbour_list command can then be run with the created cfg file from previous step, and we just need to follow the prompt to provide answers to those questions about the center and surrounding atoms, the maximum distance between them and the output file. Multiple files

Texture Correction for Fe45Cr

1. It seems this sample is with stronger texture effect, causing weird behavior in the high angle region. If you grab the files ending with "_corrected_bkg_rm_fittedbkg.dat", you will see the input data for the second stage correction. Those files are the scattering patterns for each of the 2Theta band after the first stage correction and background subtraction. For the background subtraction, we fitted an exponential function with the form of 'a + b * exp[-c * Q^2]' and after the subtraction, we expect the pattern sitting on the baseline, i.e., 0. Here below I am showing some of the patterns with the background subtracted, from which you can see the weird effect in the patterns for 157 and 162. For the two regions labeled out with red arrows, there are no peaks at all for 157 and 162, in which case there is no hope for any corrections and therefore we have to remove them. To do this, we can either delete all files corresponding to the two 2Theta's. Or, we can change the input change file to remove them from group. You can find my latest input json file at /SNS/users/y8z/NOM_Shared/Yuanpeng/texture_correction_Mar2025/Fe45Cr_ZYP/ttheta_group_params_new_new_new_new_new_new_new.json

   

2. Though we implemented the background subtraction before the second stage correction, still sometimes the patterns are not perfectly suitable for the integration purpose. In some regions, the pattern is either above the baseline by a bit offset or part of the peak is below the baseline. This makes the peak area calculation and therefore the spherical harmonics fitting inaccurate, yielding weirdly looking outcome. For example, if part of the peak is below the baseline, there are some negative intensities, potentially making the overall intensity close to 0. The fitted coefficient then could be very big, leading to a huge peak with part of the peak above and part of the peak below the baseline. To solve the issue, I did change the script a bit to offset the pattern after the background subtraction to make sure we don't have any negative intensity. The new script is located at /SNS/users/y8z/NOM_Shared/Yuanpeng/texture_correction_Mar2025/Fe45Cr_ZYP/texture_proc_real_1step_not_aligned_2step_aligned.py

3. The original chunk definition is too coarse in some regions for both group-1 and group-2. You can find the chunk definition in my new json file mentioned above.

Steps for Texture Correction

1. First, we need to prepare the grouping file, which will divide detectors into small groups according to the polar and azimuthal angles. The MantidTotalScattering (MTS) reduction will then take the grouping file for reducing data into those small groups.

   • Go to /SNS/NOM/shared/scripts/texture and run the texture_group_gen.py script like this,

     mantidpython texture_group_gen.py