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16: Collisions and Scattering

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    Collisions among molecules can also be viewed as a problem in time-dependent quantum mechanics. The perturbation is the "interaction potential" and the time dependence arises from the movement of the nuclear positions.

    • 16.1: One Dimensional Scattering
      Atom-atom scattering on a single Born-Oppenheimer energy surface can be reduced to a one-dimensional Schrödinger equation by separating the radial and angular parts of the three-dimensional Schrödinger equation in the same fashion as used for the Hydrogen atom.
    • 16.2: Multichannel Problems
      When excited electronic states are involved, couplings between two or more electronic surfaces may arise. Dynamics occuring on an excited-state surface may evolve in a way that produces flux on another surface.
    • 16.3: Classical Treatment of Nuclear Motion
      For potentials of typical chemical bonding and for all but low-energy motions of light particles such as Hydrogen and Deuterium nuclei or electrons, the local de Broglie wavelengths are often short enough to treat the nuclear-motion dynamics of molecules in a purely classical manner, and to apply so-called semi-classical corrections near classical turning points. The motions of H and D atomic centers usually require quantal treatment except when their kinetic energies are quite high.
    • 16.4: Wavepackets
      In an attempt to combine the attributes and stregths of classical trajectories, which allow us to "watch" the motions that molecules undergo, and quantum mechanical wavefunctions, which are needed if interference phenomena are to be treated, a hybrid approach is sometimes used. A popular and rather successful such point of view is provided by so called coherent state wavepackets.

    Thumbnail: A simple schematic diagram of a two-particle scattering process. One particle is scattered on a single scattering center. The impact parameter and the differential cross section element and the solid angle element in the exit direction are marked. Their quotient is the differential cross section. (CC BY-SA 3.0; Vswitchs)

    This page titled 16: Collisions and Scattering is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Jack Simons via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.