A full dimensional direct ab initio dynamics study of the electron capture by SF6 Original Research Article

The dynamics of electron capture by sulfur hexafluoride (SF6) have been investigated by means of full dimensional direct ab initio dynamics calculations at the HF/6-311G(d)+sp (a diffuse sp-function is further added to sulfur atom) level. A rigid SF6 structure and narrow Franck–Condon region for electron capture was assumed in choosing initial conditions for the trajectories. The direct ab initio dynamics calculations for the electron capture processes by SF6 indicated that the SF−6 ion formed by the vertical electron attachment to SF6 decomposes into SF−5 and F via short-lived complex formation (SF−6). The lifetime of SF−6 was distributed from 0.1–0.2 ps, which is quite short as lifetime of the intermediate complex. The dynamics calculations showed that 12% of the total available energy is partitioned into the relative translational mode between SF5− and F. The effect of solid phase on the dynamics has been examined by introducing a model bath-relaxation time for energy dispersion. There was a possibility that the SF6− anion exists in solid phase. The mechanism of the electron capture by SF6 in gas phase and in solid phase was discussed on the basis of the results.