How-to guides

Each guide gets one task done. It starts with the goal and what you need, then gives numbered steps and a check.

• Calibrate the instrument with a standard: refine a standard once and reuse its peak shape and corrections for your samples.

• Refine a structure: refine the cell, atom positions, occupancies, displacement parameters, ions, texture and several phases.

• Model disorder near special positions: write a split site that every engine reads the same way.

• Fit single peaks: fit individual peaks without a crystal structure, in GSAS-II or TOPAS.

• Simulate a pattern: calculate a pattern from a model without fitting anything.

• Run a series: refine against many patterns in sequence, each step starting from the last.

• Use PowderLine from Python and in pipelines: validate and run recipes from your own code, and handle failures.

• Run at a beamline: the GSAS-II server, batches of recipes and unattended runs on shared workstations.

• Run TOPAS recipes: run TOPAS 6 on Windows, or write its input anywhere.

• Troubleshoot: what an error message means and how to fix it.