The structure of the CF₄^- anion and the electron affinity of the CF₄ molecule

The electronic and geometrical structure of the CF₄^- anion and its neutral parent, CF₄, are calculated with the second-order Moller-Plesset perturbation theory. Several diffuse sp shells were added to the standard 6-31+G* basis when calculating the potential energy surface of the CF₄+e^- system. It was found that the CF₄ molecule does not attach an additional electron in the ground state, i.e., the molecule possesses a zero vertical electron affinity under the Born-Oppenheimer approximation. The optimized C_3v and C_2v configurations of the anion are transition states, whereas its C_s configuration corresponds to a local minimum and is thermodynamically stable by 20 kcal/ mol. The CF₄ molecule has the negative adiabatic electron affinity of -1.22 eV with respect to this configuration of the anion.