WeSCA (standing for Weighing Scheme Convergence Algorithm) is a simple program done using Python ShelXFile package. Its main purpose is to automize weighing scheme optimization, especially if the convergence by classical methods takes longer than expected (especially for large structures).

WeSCA is distributed as a single-file executable. In order for its appropriate working one must either drop both the .hkl and .res files (with the same project names!) to the folder containing the executable or add the .exe directory to the PATH list.

The usage of WeSCA using command line is as follows:

wesca.exe [-h] [-i ITER] [-r REFINE] [-d DELTA] [-v VERBOSE] [-p PLOT] project

The parsing arguments are:

• project - name of project (same for both .res and .hkl file)
• -i or --iter - number of iterations (ShelXL runs) (20 by default)
• -r or --refine - number of refinement cycles in each iteration (10 by default)
• -d or --delta - convergence delta (0.0005 by default)
• -v or --verbose - show ShelXL output in each iteration (true by default)
• -p or --plot - show convergence plot (false by default)