Structural and electronic transition in liquid rubidium

Rubidium, like the other alkali metals, exhibits multiple structural transformations in its solid phase upon application of pressure. Recent experiments [Gorelli 2018] and calculations [Bryk 2013] suggest it also goes through a phase transformation in its liquid state, along the 573K isotherm, slightly above its melting curve. We employ \textit{ab-initio} molecular dynamic simulations to study the structural and electronic characteristics of this liquid-liquid transition. Applying the quasi-crystalline model (QCM) we find that the short-range order of liquid Rb changes abruptly from bcc-like to b-tin-like at pressures between 14-20 GPa. The electronic structure of liquid Rb is investigated in order to reveal the underlying mechanism of this transition, which we claim is not related to the Peierls transition but rather to the electronic band structure.