Quantum chemical ab initio calculations of the magnetic interaction in alkalithioferrates(III)
Quantum chemical ab initio calculations of the magnetic interaction in alkalithioferrates(III)
复制标题
碱硫铁酸盐(III)中磁相互作用的量子化学从头算
DOI：
--
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
H. Stoll
中科院分区：
文献类型：
--
作者：
Martin Mödll;M. Dolg;P. Fulde;H. Stoll
对两种三元硫代高铁酸盐晶体Na_5FeS_4和Na_3FeS_3进行了量子化学从头计算。采用250个优化点电荷的团簇模型方法研究了孤立的[FeS 4]5-和[Fe 2S 6]6-配合物的电子和磁性。特别是，弱的反铁磁耦合的两个半填充的Fe 3D壳层的二聚络合物内的活性电子的方法进行了讨论。本文分析了在10个活动轨道上有10个活动电子的完全活动空间自洽场（CASSCF）波函数，给出了Fe原子局域自旋和局域电荷涨落的期望值，定量讨论了原子间和原子内的非动力学关联。CASSCF与海森堡哈密顿量有明显的偏差，耦合常数从J（4→5）=−18 cm−1到J（0→1）=−27 cm−1，比实验小4倍。超越活性电子方法的必要性。
Quantum chemical ab initio calculations for two ternary thioferrate crystals, Na5FeS4 and Na3FeS3, have been performed. Using a cluster model approach with 250 optimized point charges for the single well-isolated complexes [FeS4]5− and [Fe2S6]6−, the electronic and magnetic properties are investigated. In particular, the weak antiferromagnetic coupling of two half-filled Fe 3d shells in the dimeric complex is discussed within the active-electron approach. The complete active space self-consistent-field (CASSCF) wave functions with 10 active electrons in 10 active orbitals are analyzed by expectation values for the local spin and the local charge fluctuations at one Fe site, allowing for a quantitative discussion of interatomic and intraatomic non dynamical correlation. With CASSCF a clear deviation from the Heisenberg Hamiltonian is found with coupling constants ranging from J(4→5)=−18 cm−1 to J(0→1)=−27 cm−1, which is a factor 4 smaller than experiment. The need of going beyond the active-electron approa...