Abstract by David Anderson
Physics and Astronomy
Applying Symmetry Modes to Rietveld Refinement
Rietveld analysis is a technique for determining the atomic structure of a crystalline material from x-ray or neutron powder diffraction data, and is useful for quantifying the symmetry-breaking distortions that arise in crystal-crystal phase transitions. Because the symmetry-mode parameter set (basis functions of irreducible representations or "irreps") is very often the most natural and compact description of a phase transition, the ability to directly refine symmetry-mode amplitudes rather than traditional atomistic parameters has proven to be highly advantageous. I am working to enable direct symmetry-mode refinements in widely-used Rietveld-analysis packages.