Structure, stability, and vibrational fundamentals of low-lying isomers of

Quantum chemical calculations have been used to determine the structures, energies, and optical parameters of isomers of C 6 H 7 + – a molecule of interest in the field of astronomy. Optimized geometries, harmonic and anharmonic vibrational frequencies, rotational constants, and dipole moments were estimated. The predicted vibrational spectrum of protonated benzene was compared with previously reported high-level ab initio calculations and experimental data to verify the correct functional was used. In the present study, several branched and cyclic isomers were found, and the vibrational fundamentals of these isomers were predicted for the first time. This data may assist in the identification of these species in the laboratory and in space.