The electron localization and the corresponding chemical interactions that govern the structures of elemental metals

Elemental metals are the simplest solid form of matter, and yet their structure variations across the periodic table and under pressure remain puzzling for many decades. They adopt and transform between very simple structures in an intriguing pattern under zero and high compressions. While most transition metals are only found in simple structures so far, the “simple” alkali and alkaline earth metals may transform into complicated structures under high pressure. Despite that quantum mechanics calculations can reproduce and/or predict most of the metal structures and many aspects of the electronic structures have been applied to explain the results, we do not know a simple, real-space, and universal mechanism that directly elucidates all the structure patterns and evolutions. Here, by employing large-scale high-throughput calculations, we demonstrate a surprisingly simple and all-embracing theory that emerges after replacing the orthodox metallic bond concept with a new perspective emphasizing the electron localizations at the interstitials. The success of this exceedingly simple and universal mechanism demonstrates that intricate chemistry resides in metals and governs their fundamental properties, and the chemical interactions of localized electrons inside metals are necessary additions to the current chemical bond theory of metals and solid states.