Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, C/Marcel.lí, Domingo, s/n, 43007, Tarragona, Spain.
Phys Chem Chem Phys. 2010 Mar 20;12(11):2716-21. doi: 10.1039/b920442c. Epub 2010 Jan 27.
The most stable spin configuration in the Cu(20) unit embedded in the P(8)W(48)O(184) POM framework has been analyzed with ab initio computational methods. Because of the large size of the Cu(20) unit, a fragment approach has been adopted to compute the four possible magnetic interactions. Difference Dedicated Configuration Interaction results reveal that the magnetic coupling between unpaired copper electrons ranges from ferromagnetic (J = 14.8 cm(-1)) to antiferromagnetic (J = -72.6 cm(-1)). With the four calculated J-values we have performed a simulation of the magnetic susceptibility vs. temperature by using the Ising model and a Monte Carlo algorithm to sample the spin configurations. The most stable spin alignment, governed by the most intense antiferromagnetic interaction, features 12 up and 8 down spins. There is no full cancellation of spins that can comply with the magnetic interactions found for this molecule.
采用从头算计算方法分析了嵌在 P(8)W(48)O(184) POM 骨架中的 Cu(20)单元的最稳定自旋构型。由于 Cu(20)单元的尺寸较大，采用了片段方法来计算四种可能的磁相互作用。差分专用组态相互作用结果表明，未配对铜电子之间的磁耦合范围从铁磁（J = 14.8 cm(-1))到反铁磁（J = -72.6 cm(-1))。利用计算得到的四个 J 值，我们通过伊辛模型和蒙特卡罗算法对磁化率与温度的关系进行了模拟，以采样自旋构型。最稳定的自旋排列受最强的反铁磁相互作用控制，其特征是 12 个向上自旋和 8 个向下自旋。没有完全抵消自旋，这可以符合该分子的磁相互作用。
