Novel rubidium polyfluorides with F3, F4, and F5 species*

Abstract

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.