Theoretical studies of d?span style='font-style: italic'>d and d¨C¦Ð?span style='font-style: italic'>d magnetic interactions in (EDT-TTFVO)₂FeBr₄ crystals

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• 作者：Mao Takenaka ; Takashi Kawakami ; Akira Ito  ; ;   ; ^{aito@chem.sci.osaka-u.ac.jp} ; Keiji Kinoshita ; Yasukata Kitagawa ; Shusuke Yamanaka ; Kizashi Yamaguchi ; Mitsutaka Okumura
• 关键词：Molecular magnetism ; Organic superconductor ; Effective exchange integral ; Ab initio MO method ; Density functional method ; EDT-TTFVO ; FeBr₄
• 刊名：Polyhedron
• 出版年：2011
• 出版时间：28 November 2011
• 年：2011
• 卷：30
• 期：18
• 页码：3284-3291
• 全文大小：989 K

文摘

The effective exchange integrals (J(HB)) of the Heisenberg spin model have been evaluated by using the ab initio MO and based on Hartree¨CFock (HF) and density functional theory (DFT) for organic magnetic metals, the (EDT-TTFVO)₂FeBr₄ crystal based on the X-ray crystallographic structures at 113 K. In order to study the magnetic properties, we proposed some of the pairs, where the direct (d?i xmlns="""">d) and indirect (d¨C¦Ð?i xmlns="""">d) magnetic couplings between Fe(III) d-spins (S = 5/2) without/with ¦Ð-dimer spins (S = 1/2) were calculated, respectively. The effective exchange integrals were evaluated by using UB3LYP method, and principal J values were 0.5, ?.1 and 0.4 K. From these results, it is found that there were three dimensional spin arrangements of Fe(III) d-spins. The Quantum Monte Carlo (QMC) simulations had been carried out with our calculated J values to evaluate the magnetic susceptibility for this molecular crystal, reproducing the experimental tendency.