Chemical Principles of Topological Semimetals*

Chemical principles can be a powerful tool for predicting, understanding and synthesizing new topological materials. In this talk I will introduce these concepts. A common practice in solid state chemistry is to connect structural motifs with properties. In this sprit, I will focus on a common structural motif, a square-net arrangement of atoms. I will explain how simple chemical rules, for example electron counting or geometrical considerations, such as atomic distances, can be used for identifying topological semimetals in such compounds. By connecting the crystal structure to the electronic properties, we can define a tolerance factor, solely based on atomic distances, which separates square-net -based nodal line semimetals from other trivial compounds. The talk is largely based on these two references [1,2].

[1] Schoop, Pielnhofer, Lotsch, Chem. Mater. 30 (8), 2557-2565 (2018_
[2] Klemenz, Lei, Schoop, Arxiv:1808.06619