Calculation of vertical and adiabatic ionization potentials for some benzaldehydes using hybrid DFT, multilevel G3B3 and MP2 methods

The adiabatic ionization potential (AIP) and vertical ionization potential (VIP) for eight benzaldehydes were calculated using DFT (B3LYP, CAM-B3LYP and ωB97XD), MP2, G3B3 and CBS-QB3 methods. Basis set dependence was checked using four different basis sets 6-311G(d,p), 6-31+G(d,p), 6-311++G(2df,2p) and cc-pVTZ. Computed results were compared with the experimental data. Error metrics and statistical tools were used to validate the methods tested. Results showed an excellent agreement between the computed results and the experimental ones. Nature of the substituted groups and solvent effect on AIP values were investigated. Changes in the geometrical structures of cationic species were compared with neutral ones.