Temperature-induced electride transition in dense lithium

As a prototypical light metal, lithium shows various and intriguing behaviors including electride character under high pressure. It has a pronounced melting line depression from 40 to 60 GPa, yet a precise and detailed understanding of this melting minimum remains elusive. Here, using computations that include metadynamics, crystal structure searching, and molecular dynamics with machine learned potentials, we demonstrate a temperature-induced electride (pocketlike to tubelike) transition accompanied by complex structural phase transitions in dense premelting lithium. The possible rearrangement of nearest neighbors from three-coordinated net to dimers and the premelting collective atomic motion affected by this electronic transition demonstrates the combined influence of temperature and electronic structure on the high-pressure behaviors of metals.