This research article published by Science of Publishing Group, 2015In this study, the geometrical structure and vibrational spectra of the trimer molecule Rb3F3 and ionic clusters Rb2F + , RbF2 – , Rb3F2 + , and Rb2F3 – were studied by density functional theory (DFT) with hybrid functional B3P86 and Møller–Plesset perturbation theory of second order (MP2). The effective core potential with Def2–TZVP (6s4p3d) basis set for rubidium atom and aug–cc–pVTZ (5s4p3d2f) basis set for fluorine atom were used. The triatomic ions have a linear equilibrium geometric structure of D∞h symmetry, whereas for pentaatomic ions Rb3F2 + , Rb2F3 – and trimer molecule Rb3F3 different isomers have been revealed. For the ions Rb3F2 + , Rb2F3 – three isomers were confirmed to be equilibrium; the linear (D∞h), the planar cyclic (C2v) and the bipyramidal (D3h) while for trimer Rb3F3, two isomers were found; the hexagonal (D3h) and the “butterfly-shaped” (C2v)