SEMI-CLASSICAL MODEL FOR ACCIDENTAL PREDISSOCIATION IN DIATOMIC-MOLECULES

After a short review of possible quantum treatments, the uniform semiclassical theory of Child (J. Mol. Spectrosc. 53, 280 (1974)) is applied to the problem of accidental predissociation in a diatomic molecule where a bound state dissociates into a continuum via a coupling with a near-degenerate second bound state. A complete connection diagram and an analytical expression for the lineshape is provided. This expression is used in the diabatic limit to derive the widths and shifts of the resonances. Checks are made for two test cases for which a simplified quantum model leads to analytical formulas. The familiar case in which each resonance shares the initial width of the perturbing state according to its weight in the configuration interaction wavefunction is verified. In the opposite coupling scheme, the resonance narrowing phenomenon predicted by the quantum model is also obtained. Copyright © 1980 by Academic Press, inc.