Mainz 1997 – scientific programme

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A: Atomphysik

A 2: e-Streuung I

A 2.1: Talk

Monday, March 3, 1997, 16:00–16:15, P5

Quantum-classical correspondence of top-of-barrier motion — •W. Ihra, F. Mota-Furtado, and P. F. O’Mahony — Dept. of Mathematics, Royal Holloway, Univ. of London, Egham, Surrey TW20 0EX, UK

When three charged particles break up at low energies the dominant break up configuration is the Wannier mode: The motion takes place along a reaction coordinate where the three particle potential has a local maximum in one of the coordinates perpendicular to it. In the case of the maximum having the form of an inverted harmonic oscillator we explain why the quantum [2] and the classical analysis [1] lead to identical threshold laws for the break-up cross section. In contrast, the quantum mechanics of models where the local maximum has the form of a cusp differs dramatically from its classical counterpart: While classically ionization is forbidden in an energy interval even above total energy zero [3], quantum mechanically the break-up still takes place on top of the potential barrier [4,5]. By analyzing the classical limit of the quantum mechanical threshold law for top-of-cusp motion we are able to explain the different behavior in the two limits.

[1] G. Wannier, Phys. Rev. 90, 817 (1953)

[2] J. H. Macek, S. Yu. Ovchinnikov, Phys. Rev. A 49, R4273 (1994)

[3] G. Handke, M. Draeger, W. Ihra, H. Friedrich, PRA 48, 3699 (1993)

[4] W. Ihra, M. Draeger, G. Handke, H. Friedrich, PRA 52, 3752 (1995)

[5] J. H. Macek and W. Ihra, Phys. Rev. A, submitted (1996)