Communication: Highly accurate ozone formation potential and implications for kinetics

Communication: An accurate global potential energy surface for the ground electronic state of ozone

“…The electronic structure in the bottleneck region was the main subject of our previous study with many details provided in the supplementary material of that paper. 15 To briefly summarize, we found that the height of the submerged reef and depth of the vdW well are substantially reduced by both basis set and active space completeness. We followed the switch in character between the ground state and an excited state correlated with O 2 ( 1 g ) + O( 1 D g ) products and noted that if all 13 singlet states were included using a dynamically weighted state-averaged method 25,26 (DW-SA-CASSCF), then the transition was better behaved and the reef all but disappeared.…”

“…21 As we have reported previously, D e for standard MRCI varies with basis set from 7927 cm −1 a) Electronic addresses: dawesr@mst.edu and hguo@unm.edu at the AVTZ level to 8768 cm −1 at the AV6Z level, an increase of more than 800 cm −1 . 15 This makes complete basis set (CBS) extrapolation uncertain and we previously noted a variation of ∼150 cm −1 between various CBS schemes. 15 The large effect of the Davidson correction (>300 cm −1 ) on D e is evidence of the importance of high-order correlation.…”

“…15 This makes complete basis set (CBS) extrapolation uncertain and we previously noted a variation of ∼150 cm −1 between various CBS schemes. 15 The large effect of the Davidson correction (>300 cm −1 ) on D e is evidence of the importance of high-order correlation. 22 Dynamic correlation is very important in general, since D e at the full-valence complete active space self-consistent field (CASSCF) level is only 3003 and 3104 cm −1 for the VTZ-F12 and VQZ-F12 basis sets, 23 respectively, and the shape of the minimum energy path (MEP) towards dissociation changes qualitatively with the inclusion of dynamic correlation.…”

“…[7][8][9][10] Perhaps the biggest limitation for achieving agreement between theory and experiment has been the lack of an entirely satisfactory potential energy surface or surfaces (PESs). [11][12][13][14][15][16] Here, we focus on the development of an accurate PES for the ground state based on explicitly correlated multireference configuration interaction (MRCI-F12) 17, 18 data computed using MOLPRO, 19 which can be used to make accurate predictions of the kinetics and dynamics.…”

Dynamics of the O-Atom Exchange Reaction 16O(3P) + 18O18O(3Σg–) → 16O18O(3Σg–) + 18O(3P) at Hyperthermal Energies

“…24 This PES for the O + O 2 system is characterized by a deep well corresponding to O 3 , with a submerged potential barrier ("reef") in the O + O 2 entrance/exit channel, now thought to be an artifact. [25][26][27] If the complex lived long enough, then the energy would be completely randomized among the degrees of freedom, and the products would be scattered into all spatial directions with equal probability, corresponding to a forward-backward symmetric c.m. angular distribution.…”