Ab initio study of the magnetic behavior of four dithiadiazolyl radical compounds |
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| Institution: | 1. Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, C/Pedro Cerbuna 12, 50009 Zaragoza, Spain;2. Institut Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France;3. Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK;1. Quantum Beam Science Center (QuBS), Japan Atomic Energy Agency (JAEA), Watanuki-machi 1233, Takasaki, Gunma, 370-1292, Japan;2. Department of Material Science, Sophia University, Tokyo, 102-0094, Japan;3. Department of Engineering, Ibaraki University, Hitachi, 615-8510, Japan;4. Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science @ MLZ, Lichtenbergstraße 1, D-85747, Garching, Germany;5. Jülich Centre for Neutron Science & Institute for Complex Systems, Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany;1. Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan;2. Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA 01375, USA;3. Tokyo Institute of Technology, Chemical Resources Laboratory, R1-17, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan;1. Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry, Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany;2. Institute of Toxicology and Genetics, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany;3. Chemistry, Physics and Mechanical Engineering School (CPME), Queensland University of Technology (QUT), PO Box 2434, 2 George Street, Brisbane, 4000 QLD, Australia |
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| Abstract: | We have studied, by means of ab initio calculations, the magnetic interaction mechanisms in four radical crystals, X–C6F4–CNSSN (X = O2N, α-NC, β-NC, Br), which has allowed us to explain their different magnetic behaviour (ferromagnetism, antiferromagnetism, paramagnetism, spin frustration, etc.). First, we have identified the magnetic exchange pathways considering those with distances between two atoms of different dithiadiazolyl rings shorter than 7 Å and those with an intermolecular distance between an atom of the heterocyclic ring and an atom in a neighbouring radical shorter than 4 Å. Second, the calculations have been carried out in the framework of the DFT Broken Symmetry. Following this procedure we have determined the magnitude and the sign of the relevant coupling constants for the X–C6F4–CNSSN (X = O2N, α-NC, β-NC, Br) radicals. In the cases where the radicals order magnetically, ordering temperatures determined with our ab initio calculations agree very well with the experimental ones. Thus, in the case of the O2N derivative ferromagnetic ordering is observed below 1.3 K, in very good agreement with an ordering temperature around 1.6 K predicted from our calculated exchange constants and using a mean field approximation. |
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