Puzzling Lack of Temperature Dependence of the PuO2 Magnetic Susceptibility Explained According to Ab Initio Wave Function Calculations

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• 作者：Frédéric GendronJochen Autschbach
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2017
• 出版时间：February 2, 2017
• 年：2017
• 卷：8
• 期：3
• 页码：673-678
• 全文大小：399K
• ISSN：1948-7185

文摘

The electronic structure and the magnetic properties of solid PuO₂ are investigated by wave function theory calculations, using a relativistic complete active space (CAS) approach including spin–orbit coupling. The experimental magnetic susceptibility is well reproduced by calculations for an embedded PuO₈^12– cluster model. The calculations indicate that the surprising lack of temperature dependence of the magnetic susceptibility χ of solid PuO₂ can be rationalized based on the properties of a single Pu⁴⁺ ion in the cubic ligand field of the surrounding oxygen ions. Below ∼300 K, the only populated state is the nonmagnetic ground state, leading to standard temperature-independent paramagnetism (TIP). Above 300 K, there is an almost perfect cancellation of temperature-dependent contributions to χ that depends delicately on the mixing of ion levels in the electronic states, their relative energies, and the magnetic coupling between them.