Chapter 5: From Nuclear Fluxes During Tunnelling to Electronic Fluxes During Charge Migration
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Published:22 Sep 2020
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Special Collection: 2020 ebook collection
D. Jia, J. Manz, A. Schild, V. Svoboda, and Y. Yang, in Tunnelling in Molecules: Nuclear Quantum Effects from Bio to Physical Chemistry, ed. J. Kästner and S. Kozuch, The Royal Society of Chemistry, 2020, ch. 5, pp. 167-191.
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Two case studies of nuclear and electronic quantum dynamics reveal close analogies in entirely different molecular model systems. The first one is stereomutation of the CHFBr radical by periodic nuclear tunnelling, the second one is periodic electronic charge migration in the HCCBr+ cation. We consider rather simple model scenarios, i.e. the systems are oriented, they are prepared as a superposition of the corresponding ground plus first excited states, they evolve essentially along one degree of freedom, and we neglect effects of decoherence. In spite of the large differences in the systems and processes – e.g. the periods for tunnelling τstereo=10.57 ps and for charge migration τchm=1.51 fs differ by four orders of magnitude – the time evolutions of the corresponding nuclear and electronic densities and fluxes exhibit many (at least eight!) common features. These analogies suggest – as a working hypothesis – that not only stereomutation of CHFBr but also electronic charge migration in HCCBr+ share common aspects of tunnelling, namely nuclear potential tunnelling and electronic dynamical tunnelling, respectively.