Application of topological quantum chemistry in electrides

The recently developed theory of topological quantum chemistry (TQC) has built a close connection between band representations in momentum space and orbital characters real space. It provides an effective way to diagnose materials, leading the discovery lots materials after screening all known nonmagnetic compounds. On other hand, it can also efficiently reveal spacial characters, including average charge centers site-symmetry characters. By using TQC with computed irreducible first-principles calculations, we demonstrate that electrides excess electrons serving as anions at vacancies be well identified by analyzing (BRs), which cannot expressed sum atomic-orbital-induced (aBRs). In fact, floating bands (formed electrons) belong BRs induced from "pseudo-orbitals" centered vacancies. words, are proved unconventional ionic crystals, where set occupied is not aBRs but necessarily contains BR promising avenue pursue more electride candidates crystals.