Symmetry-Breaking in Crystals

Dr. Branton J. Campbell
Department of Physics and Astronomy
Brigham Young University


Group-representation theory (GRT) is a critical layer in the bedrock of modern chemistry and physics.  Its reach includes any physical or mathematical system that exhibits any kind of symmetry, even the universe itself, and provides a unique parameter set for describing structures that break the parent symmetries of a system.  I'll describe the role of GRT in the science of symmetry breaking in crystalline materials, and the new infrastructure we have built to enable a broad range of applications, including the compact description of general order-parameter types (displacive, magnetic, rigid-unit-rotational, occupational, lattice-strain, etc.), a common parameter set for the phases of a complicated phase diagram, the solution of large and subtle superstructures, the analysis of local order in disordered crystals, and the characterization of incommensurately modulated crystals.