Molecular and Ionic Clusters of Rubidium Fluoride: Theoretical Study of Structure and Vibrational Spectra

Abstract

In this study, the geometrical structure and vibrational spectra of the trimer molecule Rb 3 F 3 and ionic clusters Rb 2 F + , RbF 2-, Rb 3 F 2 + , and Rb 2 F 3 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 Rb 3 F 2 + , Rb 2 F 3 and trimer molecule Rb 3 F 3 different isomers have been revealed. For the ions Rb 3 F 2 + , Rb 2 F 3 three isomers were confirmed to be equilibrium; the linear (D∞ h), the planar cyclic (C 2v) and the bipyramidal (D 3h) while for trimer Rb 3 F 3 , two isomers were found; the hexagonal (D 3h) and the "butterfly-shaped" (C 2v) configuration.

Theoretical Study of Structure and Vibrational Spectra of Molecular and Ionic Clusters Existing in Vapour over Rubidium Chloride

“…When comparing the properties of Rb 3 Cl 3 with Rb 3 F 3 molecule, a similarity may be noted: the same two isomers were revealed for Rb 3 F 3 [21] and the butterfly-shaped isomer was predominant in that case as well.…”

“…The relative concentration of isomers p(C 2v )/p(D 3h ) have been estimated using the same procedure as it was described previously [21]. The enthalpy of the isomerization and relative energy of isomers ∆ r E iso (MP2) for the isomerization reaction Rb 3 Cl 3 (D 3h ) ⇌ Rb 3 Cl 3 (C 2v ) was calculated using Eqs.…”

“…To investigate the structure and properties of alkali halide clusters, different experimental techniques e.g. high temperature mass spectrometry [12,13], microwave absorption spectroscopy [14,15] and molecular beam electric resonance [16] and theoretical methods [1,[17][18][19][20][21] were employed.…”