Topography of potential-energy surfaces. DIM (diatomics-in-molecules) surface for F + F2

Abstract

Potential-energy surfaces have been calculated over the full range of nuclear configurations for the F + F2 reaction using the DIM (diatomics-in-molecules) method with the 28 polyatomic basis functions of 2A' symmetry and the 26 of 2A" symmetry arising from three F(2Pu) atoms.The lowest 2A' surface has its lowest potential-energy barrier Eb = 72 kJ mol-' in a configuration bent by ca. 30 O from the collinear configuration with 'Zg symmetry. The lowest 2A" surface has its lowest barrier Eb== 108 kJ mol-' in the collinear configuration with 'nu symmetry. The lowest 2A" surface shows a stronger preference for the collinear configuration than does the lowest 2A' surface, in accordance with the predictions of Walsh rnolecular-orbital theory.

Reactive scattering of a supersonic fluorine atom beam: F + Cl2

“…DIM calculations have recently been undertaken [9] on the F + F 2 and C1 + C12 potential energy surfaces including spin orbit interaction, which indicate that some non-adiabatic transitions may occur between F(2P1/2) and F(2P3/z) spin multiplet states with splitting F(2P1/2)-F(2P3/2)= 5 kJ tool-1, in near collinear configurations in the entrance valley of the F + C12 potential energy surface. However reaction can proceed only on the lowest 2E+ 2A' potential energy surface which involves a shallow minimum, since the higher lying 21-I-2A', 2A" potential energy surfaces involve a significant barrier [7,8]. The 2~+-2-4' potential energy surface correlates with the CI(zP3/2) ground spin multiplet state of the product C1 atom.…”

“…Ab initio calculations on the C1F 2 radical [6] show it to be bent with an interbond angle fl-,~ 148 ~ and a C1-F bond length r e = 1'72A slightly extended over the bond length of the diatomic r~(ClF) = 1'63 A [-22]. Similarly DIM calculations on the F + F 2 [7] and C1 + el 2 [8] potential energy surfaces predict transition states which are bent with interbond angles fl ~ 150~ ~ and with the F-F and C1-C1 bond lengths slightly increased over the corresponding diatomic bond lengths [22]. Accordingly the structure of the F Cl-C1 complex may be estimated as shown in figure 5, together with an estimated reactant transition state having the same interbond angle fl and an gxtended C1-F bond length.…”

“…However this work has been confined to the heavier halogen atoms and molecules and theoretical estimates of the topography of the reaction potential energy surfaces have therefore been confined to the qualitative indications of Walsh [5] triatomic molecular orbital theory. The structure of the C1F 2 radical has been studied by ab initio methods [6] and potential energy surfaces have been calculated by the diatomics-in-molecules (DIM) method for the F + F 2 [7] and C1 + C12 [8], with spin orbit interaction being included in more recent calculations [9]. Calculations have also been reported on the full range of triatomic radicals involving F and C1 atoms using the MINDO method [I0].…”

Reactive scattering of a supersonic fluorine atom beam: F + Br2

“…Recent DIM calculations on the F + F 2 [15] and C1 + C12 [16] potential energy surfaces which have been extended to include spin orbit interaction [17], suggest that some non-adiabatic transitions may occur between the F(2Pt/2) and F(2P3/2) spin multiplet states in the entrance valley of the F + Br 2 potential energy surface due to the small spin orbit splitting F(2P1/2)-F(2p3/2)= 5 kJ mot -1. However the lowest 2E+-2A' potential energy surface correlates the reactant F(aP3/2) ground state with the Br(2p3/2) ground state product without an intervening energy barrier.…”

Three Dimensional Potential Energy Surface For The F3

“…Therefore, three dimensional potential energy surface of the F 3 is very interesting. Duggan and Grice have described the approximate shape of the potential energy surface of F 2 + F [1]. Artau and Nizzi [2], who used to determine the dissociation energy of the F 2 bond by the collision-induced dissociation energy method.…”