Estimation of Off-Site Coulomb Integrals and Phase Diagrams of Charge Ordered States in the θ-Phase Organic Conductors
Estimation of Off-Site Coulomb Integrals and Phase Diagrams of Charge Ordered States in the θ-Phase Organic Conductors
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θ相有机导体中的场外库仑积分和电荷有序态相图的估计
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
Takehiko Mori
中科院分区：
文献类型：
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作者：
Takehiko Mori
计算了BEDT-TTF（bis（ethylenedithio）tetrathiafulvalene）分子的最高占据轨道（HOMO）的库仑斥力V。裸V是在点电荷近似下容易估计的量。只要实际晶体中的屏蔽V与计算出的裸V成正比，通常的θ相倾向于水平或对角条纹，而垂直条纹在小二面角的极限（金属极限）变得相对稳定。结合静电荷分布（原子极限）和Stoner模型（推广的Stoner模型）讨论了θ相的相图。该模型包含两个序参数：自旋极化，Sz，和电荷的顺序，n-1/2。该模型解释了为什么Rb盐在190 K以下的绝缘态是顺磁电荷有序态，而Cs盐在20 K以下具有不同的绝缘相。研究了三聚体的晶格二聚化。
Intermolecular Coulomb repulsion, V, of the highest occupied molecular orbitals (HOMO) of BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) is calculated for various molecular geometries. The bare V is a quantity that is easily estimated under the point charge approximation. As far as the screened V in actual crystals is proportional to the calculated bare V, the usual θ-phase prefers the horizontal or diagonal stripe, whereas the vertical stripe becomes comparatively stable in the limit of the small dihedral angle (in the metallic limit). The phase diagrams of the θ-phase are discussed under the combination of the static charge distribution (the atomic limit) and the Stoner model (the extended Stoner model). The model contains two order parameters: the spin polarization, Sz, and the charge order, n-1/2. This model explains why the insulating state of the Rb salt below 190 K is a paramagnetic charge-ordered state, while the Cs salt has a different insulating phase below 20 K. The lattice dimerization of th...