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Updated: Oct 25, 2026
All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics
Published on: January 19, 2018
Real-Time CASSCF Ehrenfest (TD-CASSCF) Modeling of Spintronics in a Tetrathiafulvalene-Based Nitronyl Nitroxide
Mercè Deumal1, Jordi Ribas-Ariño1, Michael A Robb2
1Departament de Ciència de Materials i Química Física & IQTCUB, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1, BarcelonaE-08820, Spain.
Abstract:
Using real-time all-electron TD-CASSCF/Ehrenfest simulations, we investigate the molecular origin of magnetoresistance in the organic material BTBN, a tetrathiafulvalene-nitronyl nitroxide diradical. The calculations reveal that charge transport and spin dynamics are strongly coupled. In the high-spin state, where localized spins are aligned in parallel, charge propagates efficiently through the π-stacked system via coherent wave-like migration. In contrast, in low-spin states containing antiparallel spin alignments, the charge migration competes with the spin-permutation processes between localized radical spins. These additional spin-exchange pathways do not transfer charge but divert population away from the charge transport channel, reducing charge-transfer efficiency by roughly 50%, in the example studied, relative to the high-spin state. The simulations therefore identify the competition between electron migration and spin permutation as the fundamental molecular mechanism responsible for magnetoresistance in BTBN, explaining why magnetic-field-induced spin alignment enhances charge transport and lowers electrical resistance.
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