Hartree-Fock and density functional theory studies on ionization and fragmentation of halomethane molecules by positron impact

The fragmentation patterns of halomethane molecules CF₄, CCl₂F₂, CClF₃ and CHF₃ due to positron impact have been studied by using ab initio and density functional theory (DFT) methods. The geometries of parent molecules and fragments are optimized at HF, MP2 and B3LYP levels of theory using the 6–31+G(d, p) basis set. The calculated reaction energies agree with the experimental values. The condensed Fukui functions have been calculated using the atomic charges of the Mulliken population analysis (MPA) scheme for the halomethane molecules. The calculated condensed Fukui functions successfully predict the reactive site of the halomethane molecules for the positron, electron and radical attacks. The chemical hardness and chemical potential for the above molecules and its fragments are calculated.