Density Functional Theory Study of Magnetic Coupling in the Gd12O18 Cluster

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• 作者：Lixin Ning ; Yongfan Zhang ; Zhifeng Cui ; Mario Italo Trioni ; Gian Paolo Brivio
• 刊名：Journal of Physical Chemistry A
• 出版年：2008
• 出版时间：December 25, 2008
• 年：2008
• 卷：112
• 期：51
• 页码：13650-13654
• 全文大小：221K
• 年卷期：v.112,no.51(December 25, 2008)
• ISSN：1520-5215

文摘

The magnetic properties of the Gd₁₂O₁₈ cluster cut from the bulk Gd₂O₃ crystal are investigated using the spin-polarized density functional theory within the broken-symmetry approach. Our work reveals that in the ground state of the cluster the antiferromagnetic coupling between adjacent Gd (4f⁷) spins is preferred energetically. This result is in contrast to a recent prediction made by Pedersen and Ojame ( Pedersen, H.; Ojame, L. Nano Lett. 2006, 6, 2004) but is consistent with recent experimental observations. The optimized structures of the cluster in the lowest-energy broken-symmetry state and the highest-spin ferromagnetic state are almost identical. The latter state is 71.5 cm⁻¹ higher in energy than the former one, giving a value of about −0.24 cm⁻¹ for the magnetic coupling constant, which is comparable to that estimated from experiments on the bulk crystal. The relative energies of various 4f⁷ spin patterns of the cluster are calculated, and certain characteristics of the cluster in the lowest-energy broken-symmetry state are discussed.