Spin−Orbit Configuration Interaction Calculation of the Potential Energy Curves of Iodine Oxide

2000 ◽  
Vol 104 (13) ◽  
pp. 2999-3003 ◽  
Author(s):  
S. Roszak ◽  
M. Krauss ◽  
A. B. Alekseyev ◽  
H.-P. Liebermann ◽  
R. J. Buenker
Keyword(s):  
Potential Energy ◽  
Configuration Interaction ◽  
Potential Energy Curves ◽  
Spin Orbit

Potential-energy curves, zero-field splittings, and radiative lifetimes for low-lying states of AsH

1987 ◽  
Vol 65 (2) ◽  
pp. 155-164 ◽  
Author(s):  
Toshio Matsushita ◽  
Christel M. Marian ◽  
Rainer Klotz ◽  
Sigrid D. Peyerimhoff
Keyword(s):  
Fine Structure ◽  
Potential Energy ◽  
Ground State ◽  
Zero Order ◽  
Potential Energy Curves ◽  
Basis Set ◽  
Zero Field ◽  
Spin Orbit ◽  
Spin Orbit Interactions ◽  
Π State

Large-scale multireference configuration-interaction (MRD-CI) calculations in an atomic-orbital (AO) basis set containing up to f functions on As and d on hydrogen are employed to study the potential-energy curves of the π2(X3Σ−, a1Δ, b1Σ+), the σ → π, and the π → σ3.1Π states; a large number of σ → σ* states; and the lowest π → s,p Rydberg series. The σ → σ* states are strongly repulsive and exhibit numerous interactions with the Rydberg members causing predissociation. The probabilities for the spin-forbidden transitions from b1Σ+and a1Δ to the X3Σ−ground state as well as the zero-field splittings of theX3Σ−and A3Π states have been evaluated by employing a variational perturbation scheme in which the zero-order wave functions are MRD-CI expansions. The perturber states are determined by their spin-orbit interactions, which are calculated by employing the Breit–Pauli one- and two-electron spin-orbit operator. The radiative lifetime of the b1Σ+ state is predicted to be 0.35 ms, whereby the dominant mechanism is deactivation to the ms = ±1 component.The parallel transition is found to be much weaker. The lifetime of a1Δ is calculated to be 22 ms, whereby the process [Formula: see text] is favored. Both b–X and a–X transitions borrow their intensity primarily from the A3Π–X3Σ− transition and, furthermore, the 1Π–a1Δ and higher 3,1Π state spin-allowed transitions. The probability for the quadrupole b–a transition is evaluated to be three orders of magnitude smaller than the b–X transition. The calculated zero-field splitting of the X3Σ− ground state amounts to 101.4 cm−1, and the fine-structure splitting between the 2, 1, and 0+ components of the A3Π state evaluated to be 544.5 and 674.4 cm−1, respectively, in good accord with experimental results; whereas the calculated Λ doubling of the0+–0− fine-structure levels of the A3Π state (35.2 cm−1 vs. 44.72 cm−1) is too small in the present treatment. The dependence of spin-orbit effects and transition probabilities on AO basis sets and relativistic corrections to the zero-order Hamiltonian are discussed, and it is concluded that lifetime calculations for spin-forbidden processes in first- and second-row molecules can be extended in a fairly straightforward manner to systems with considerable spin-orbit interactions.

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