Excited Electronic States of the Cyclic Isomers of O₃ and SO₂

Abstract

The low-lying electronic states of O 3 and SO 2 in their bent and cyclic isomers up to about 10 eV are calculated using the multireference configuration interaction (MRCI) method with a standard Gaussian correlation consistent polarized triple-(cc-pVTZ) basis set. The vertical excitation energies, electron configurations, and oscillator strengths of these states are reported. The molecular orbital structures and excited states of the cyclic isomers are discussed in relation to the bent ones. Coherent anti-Stokes Raman spectroscopy (CARS) schemes for detecting the synthesis of the cyclic isomers are suggested.

Electronic structure and bonding of ozone

“…This equilateral cyclic isomer of O 3 has not been observed experimentally, but it has been extensively studied theoretically. 5͑b͒,25-27,7͑f͒, 28,29 The best theoretical numbers so far are those of Ref. 7͑f͒ at the MRCI/cc-pV5Z level: r e = 1.438 Å and T e = 10 912.4 cm −1 , in very good agreement with the results of the present work ͑Table I͒.…”

Non-adiabatic and intersystem crossing dynamics in SO2. II. The role of triplet states in the bound state dynamics studied by surface-hopping simulations

“…In Table II, we present excitation energies at the S 0 equilibrium geometry as obtained with MR-CIS/ano-rccvdzp (see section II B). The excitation energies are systematically larger than the values obtained by Xie et al 26 , Lévêque et al 25 and Katagiri et al 20 , but they are very close to the results of Elliott et al 59 . Contrary to Xie et al 26 , we do not find the 3 B 2 state higher in energy than the other triplet states.…”

Electronic structure calculations of low-lying electronic states of O3

“…The vertical excitation energies from different methods in Table 3 have significant differences. Interestingly, the results of Grein 63 and Elliott et al 68 have average absolute deviations of only 0.05 and 0.06 eV from ours, since similar basis sets and similar un-contracted MRCISD algorithm are employed. The excitation energies of the internally-contracted MRCI According to the vertical excitation energies we can establish the correspondence between the vertical transitions and the four spectral bands mentioned above.…”

“…54 Our theoretical value of 31.57 kcal mol À1 obtained by the MRCISD (0.02)/ cc-pVTZ(6d,10f) method is in good agreement with the result of 31.36 kcal mol À1 of Qu et al by ic-MRCI/aug-cc-pVQZ 46 and 31.3 kcal mol À1 of Elliott et al by MRCI/cc-pVTZ. 68 Another important quantity is the dissociation energy D e of the ground state X ˜1A 1 from the global minimum to the lowest dissociation limit O 2 (X 3 S À g ) + O( 3 P). Many calculations have been performed to get closer to the experimental D e value of 26.105 AE 0.392 kcal mol À1 .…”