ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The nonadiabatic electronic structure and decay mechanisms of the spectroscopically analyzed A 2Π state of MgCl are studied using a unique combination of rigorous ab initio electronic structure and quantum dynamics techniques. The electronic structure treatment is based on ab initio multiconfiguration self-consistent field/first order and second-order configuration interaction wave functions [ΨaJ(r;R)] for the 1,2 2Π adiabatic electronic states. These wave functions are used to determine rigorous diabatic state wave functions using the derivative coupling matrix elements, gaJ,I(R)=〈ΨaJ(r;R) ||(∂/∂R)ΨaI(r;R)〉r, and approximate diabatic state wave functions using a diabatization procedure based on diagonalizing the dipole moment operator suggested by Werner and Meyer [J. Chem. Phys. 74, 5802 (1981)]. Near its equilibrium geometry the A 2ΠΩ state is well characterized as a regular diabatic state corresponding to Mg+(2P)-Cl−(1S).The higher vibrational levels of this state are significantly perturbed (predissociated) by the interaction with a second inverted, dissociative, diabatic state of the same symmetry corresponding to Mg0(1S)Cl0(2P). Because the fine structure splitting, E(2 2Π3/2)–E(2 2Π1/2), of the predissociating state is comparable to the vibrational spacing of the predissociated state, relativistic, spin–orbit, effects must be incorporated into the treatment of the predissociation. These relativistic effects are treated using the full microscopic Breit–Pauli spin–orbit (that is spin–orbit and spin–other–orbit contributions) operator. The coupled diabatic state representation incorporating relativistic effects is used as the basis for semiclassical and fully quantum mechanical treatments of the predissociation lifetimes and energy shifts of the A 2Π3/2,1/2 vibrational states. By correctly taking into account the mixing of the regular and inverted 1,2 2Π states the coupled state quantum scattering calculations are able to reproduce the observed "anomalous'' dependence of the fine structure splitting factor Asov.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.458957
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