Mainz 2017 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 42: Quantum Effects

Q 42.8: Vortrag

Donnerstag, 9. März 2017, 12:45–13:00, P 4

Nuclear motion is classical — •Irmgard Frank — Theoretische Chemie, Universität Hannover

The Born-Oppenheimer approximation suffers from strong and not fully understood drawbacks. One might believe, that ninety years after its invention one could omit it and compute ionic and electronic motion together having big computers. However, as the Schrödinger equation has similarities with the diffusion equation, the resulting nuclear wavefunction diffuses. The resulting potential for the electrons allows them to further diffuse again, etc., the result being a homogeneous gas of electrons and nuclei. We show that this can be avoided in a very simple way by describing the nuclei right from the beginning as classical point particles which obey the Newton equations. This approximation works well for the region of normal energies and is superior to a quantum chemical description of the nuclei.