ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
We report a rigorous ab initio study of the ground and low-lying excited-state potential-energy surfaces (PESs) of the Cl3 radical at CASSCF, CASPT2, and MRSDCI levels of theory. The ground state has two Cl(centered ellipsis)Cl2 van der Waals complexes, X˜L and X˜′B. The linear asymmetric minimum (X˜L) is 2Π, with a Cl–Cl distance r=3.90 bohr, and a Cl–M (M: the Cl2 center-of-mass) distance R=8.70 bohr. The bent asymmetric minimum (X˜′B) is of 2A′ symmetry, with r=3.90 bohr, R=6.85 bohr, and the angle between r(circumflex) and R(circumflex), γ=68.4°. Spin–orbit CI (configuration interaction) predicts that the global minimum is linear X˜L (2Π3/2) with a bond dissociation energy of De(Cl2(X)-Cl) of 280 cm−1. Low-lying doublet excited states have only one strongly bound structure, a linear symmetric A˜L (1 2Πg) state with a bond distance of 4.67 bohr. This state is bound by ∼4300 cm−1 with respect to the Cl2(3Πu)+Cl asymptote, and its minimum lies about 8700 cm−1 above the X˜L van der Waals minimum. Transition dipole moment calculations show that the A˜–X˜ transition is fully allowed. Two bound quartet minima were located. The most deeply bound was QD3h (1 4A1′) with a D3h equilibrium geometry (r=5.00 bohr) about 11 300 cm−1 above X˜L. The other state, QC2v (1 4A2) had a C2v equilibrium geometry (r1=4.83 bohr and θ=101.7°) and an energy of about 13 500 cm−1 relative to X˜L. Although Cl3(X˜) is shown to be unstable, the present results support the notion that Cl3 participates in Cl atom recombination processes. However, the energies and transition moments of the low-lying excited states are not consistent with electronic spectra that have been tentatively assigned to Cl3. © 1998 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.475668
Permalink