Real-time CASSCF Ehrenfest (TD-CASSCF) modeling of spintronics in a Tetrathiafulvalene-Based Nitronyl Nitroxide (BTBN) model: the competition between charge transfer and spin permutation
File(s)
Published online version
Author(s)
Deumal, Merce
Ribas-Ariño, Jordi
Robb, Mike
Type
Journal Article
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.
Date Issued
2026-09-02
Date Acceptance
2026-08-25
Citation
Journal of Physical Chemistry Letters, 2026
ISSN
1948-7185
Publisher
American Chemical Society
Journal / Book Title
Journal of Physical Chemistry Letters
Copyright Statement
© 2026 The Authors. Published by American Chemical Society This publication is licensed under a Creative Commons Attribution 4.0 International License.
License URL
Publication Status
Published online
Date Publish Online
2026-09-02