Novel rubidium polyfluorides with F₃, F₄, and F₅ species

Pressure has an important effect on chemical bonds and their chemical properties. The atypical compounds NaCl₃ and CsF₃ are predicted to be stable at high pressure and show unique physical and chemical properties. By using ab initio random structure searching and density functional theory calculations, we predicted multiple thermodynamically stable atypical compounds, which are RbF₂, RbF₃, RbF₄, and RbF₅ in the pressure range of 0–300 GPa. In these stable compounds, homonuclear bondings of F₃, F₄, and F₅ species are easily formed. The electron structure calculation showed that except for Fd-3m phase of RbF₂, these stable compounds are insulators and F 5p orbitals play an important role in the Fermi level. It is interesting that the compounds RbF₅ could be stable at nearly ambient pressure and 0 K which will stimulate experimental studies in the future. (paper)