A chemical theory of topological insulators.

Research on topological insulators (TIs) has experienced an exponential growth in the last few years, promising new technological applications in fields ranging from electronics to quantum computing. However, the strong condensed matter physical background that is needed to understand the exotic electronic structure of TIs has precluded its dissemination into the chemistry community. In this work we use chemistry-like models (e.g. the Hückel model) to bridge this gap. By taking bond alternating polyacetylenes as a starting point, we show how several key concepts about TIs, such as chiral symmetries or topologically-protected edge states, may be rephrased in terms of traditional chemical concepts by using Lewis resonance structures and bonding descriptors that characterize electron delocalization in real space. Overall, this Highlight should provide the background for understanding the properties of topological insulators to a broad chemistry readership.