Ab initio and density functional study of the Jahn-Teller distortion in the silane radical cation

An ab initio and density functional study is made of the Jahn-Teller distortion of the silane radical cation using Dunningʹs cc-pVTZ basis set. For this cation, the D2d, C3v, C2v and Cs structures are fully optimized and analyzed using an energy component analysis. The distortion towards the lowest energy geometry results in an increase in kinetic energy and a decrease in the electron-nuclear attraction energy, electron-electron repulsion energy and nuclear-nuclear repulsion. The exact exchange density functional methods B3LYP and B3PW91 turn out to be the methods best suited for the study of geometries, energies and vibrational spectra of these cations.