Superconductivity in RbH₁₂ at low pressures: An ab initio study

High-pressure polyhydrides are leading contenders for room temperature superconductivity. The next frontier lies in stabilizing them at ambient pressure, which would allow their practical applications. In this first-principles computational study, we investigate the potential for record-low pressure stabilization of binary superhydrides within the RbH ₁₂ 12 system including lattice quantum anharmonic effects in the calculations. We identify five competing phases for the pressure range between 0 and 100 GPa. Incorporating anharmonic and quantum effects on ion dynamics, we find the Immm I m m m and P6_3/mmc P 6 3 / m m c phases to be the most probable, potentially metastable even at pressures as low as 10 GPa. Notably, all phases exhibit metallic properties, with critical temperatures between 46 and 111 K within the pressure range they are dynamically stable. These findings have the potential to inspire future experimental exploration of high-temperature superconductivity at low pressures in Rb-H binary compounds.