Electronic signatures of ductility and brittleness

Ductility versus brittleness of a material, while singularly important in the design of devices and structures, is one of the least understood properties of materials. Using ab initio density functional theory calculations and topological analysis of electron density of tin which exhibits a brittle to ductile transition (BDT) as a function of pressure, we find that electron densities at the critical points correlate in a simple way with the relevant stacking fault and surface energetics. Rationalizing this correlation with a simple model, we use it to accurately capture trends in the BDT temperature of bcc metals and demonstrate how it facilitates cost-effective design of materials with improved mechanical properties through an example of microalloying of $MoSi_2$