Novel Group Theoretical Methods for Electron Structure Theory

This book presents the induced representation method, a powerful technique in quantum mechanics with applications in condensed matter physics. After introducing the key concepts in group theory and representation theory necessary to understate the technique, the author goes on to explore applications in electron structure theory, namely: basis sets in clusters, normal vibrations, selection rules, two-electron wavefunctions, and space-group representations. This technique allows the simplification of standard techniques for the analysis of molecular orbitals and normal vibrations of molecules. A space group approach to the wavefunction of a Cooper pair based on the Anderson ansatz and Mackey-Bradley theorem is developed, and several applications are considered, namely group-theoretical nodes, non-symmorphic groups, and unification of the group theoretical and topological approaches to the structure of Cooper pairs in unconventional superconductors.