Multicenter Bonding in Periodic Solids through the Lens of Atomic- and Molecular-Orbital Partitioning

Abstract To understand the nature of multicenter interactions in periodic solids and their associated materials (transport) properties, we investigate and quantify multicenter bonding on the basis of the underlying wave function, namely by a combination of quantum-chemical tools for a diverse series of functional materials. First, we probe all compounds by projected force constants based on plane-wave phonon calculations, followed by a projection from plane waves onto a local-orbital framework and its thorough quantum-chemical analysis. While the three-center crystal orbital bond index is used to quantify multicenter bonding between atomic orbitals, the linear combination of fragment orbitals provides a molecular-orbital lens. Eventually, both approaches are fused into the molecular orbital contribution index that directly attributes the contributions of a single molecular orbital to a multicenter bond.