Structural, electronic and magnetic properties of KMF3 (M = Mn, Fe, Co, Ni)
Structural, electronic and magnetic properties of KMF3 (M = Mn, Fe, Co, Ni)
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DOI：
10.1039/a701528c
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发表时间：
1997-01-01
影响因子：
3.4
通讯作者：
Saunders, VR
中科院分区：
文献类型：
--
作者：
Dovesi, R;Fava, FF;Saunders, VR
钙钛矿体系 KMF3（M = Mn、Fe、Co、Ni）的结构、电子和磁性特性已通过 CRYSTAL95（周期性从头算 Hartree-Fock 程序）进行了研究。使用了全电子高斯基组。首先确定了立方结构的状态方程；然后探索了立方对称性的偏差，结果发现 Mn、Fe 和 Co 系统在四方几何结构中稍微更稳定。该系统几乎完全是离子的，K 和 M 的净电荷为 + 1，约 1。 -0.9 and cn. + 1.8 \e\, respectively.反铁磁（AFM）相总是比铁磁（FM）相更稳定；能量差 Delta E = E(FM) - E(AFM) 如下所示： (a) 与 M-M 第一邻居的数量相加； (b) 根据逆幂律随着晶格参数的减小而增大； (c) 当 M-(F) over cap-M 角接近 90 度时变为零。使用 Ising 模型哈密顿量从 AE 评估的超交换耦合常数与实验数据定性一致（后者的 30% 到 45%）。马利肯布居数据、电荷和自旋密度图以及态密度用于说明电子结构。
The structural, electronic and magnetic properties of the perovskite systems KMF3 (M = Mn, Fe, Co, Ni) have been investigated with CRYSTAL95, a periodic ab initio Hartree-Fock program. An all-electron Gaussian basis set has been used. The equation of state has been determined first for the cubic structure; then deviations from cubic symmetry have been explored, with the result that the Mn, Fe and Co systems are found to be slightly more stable in a tetragonal geometry. The systems are almost fully ionic, with net charges for K and M of + 1, ca. -0.9 and cn. + 1.8 \e\, respectively. The antiferromagnetic (AFM) is always more stable than the ferromagnetic (FM) phase; the energy difference Delta E = E(FM) - E(AFM) is shown: (a) to be additive with respect to the number of M-M first neighbours; (b) to increase with decreasing lattice parameter according to an inverse power law; and (c) to become zero when the M-(F) over cap-M angle approaches 90 degrees. The super-exchange coupling constants, evaluated from AE by using an Ising model hamiltonian, are in qualitative agreement with the experimental data (from 30% to 45% of the latter). Mulliken population data, charge and spin density maps and density of states are used to illustrate the electronic structure.