Peierls transitions in ionic organic charge-transfer crystals with spin and charge degrees of freedom.
Peierls transitions in ionic organic charge-transfer crystals with spin and charge degrees of freedom.
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具有自旋和电荷自由度的离子有机电荷转移晶体中的 Peierls 跃迁。
DOI：
10.1021/jp0552022
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发表时间：
2006
影响因子：
3.3
通讯作者：
Soos Zg
中科院分区：
文献类型：
--
作者：
Bewick Sa;Soos Zg
有机电荷转移（CT）盐的准一维电子结构使π电子给体（D）和受体（A）的混合或分离堆叠中的Peierls跃迁合理化。本文提出了一个微观Peierls-Hubbard模型HCT，用于研究（Dρ+Aρ-）n和离子度ρ > 0.7的CT盐。二聚化打开了一个Peierls能隙，由于电子相关，这是单重态-三重态能隙，EST。与自旋-佩尔斯系统（如ρ = 1且TSP < 20 K的海森堡自旋链）相比，ρ < 1的CT盐中的佩尔斯跃迁发生在更高的TP，并且涉及自旋和电荷自由度。线性电子-声子耦合和谐振晶格的绝热近似被用来模拟T < TP时的二聚振幅δ（T）、磁化率（自旋）χ（T）和完全对称分子模的相对红外强度。本文对两种具有不同磁性和红外线的热重比为50和120 K的CT盐，应用了N = 12的热重比热力学。
The quasi-one-dimensional electronic structure of organic charge-transfer (CT) salts rationalizes Peierls transitions in mixed or segregated stacks of π-electron donors (D) and acceptors (A). A microscopic Peierls−Hubbard model, HCT, is presented for CT salts with mixed stacks (Dρ+Aρ-)n and ionicity ρ > 0.7. Dimerization opens a Peierls gap that, due to electron correlation, is the singlet−triplet gap, EST. In contrast to spin-Peierls systems, such as Heisenberg spin chains with ρ = 1 and TSP < 20 K, Peierls transitions in CT salts with ρ < 1 occur at higher TP and involve both spin and charge degrees of freedom. Linear electron−phonon coupling and an adiabatic approximation for a harmonic lattice are used to model the dimerization amplitude δ(T) for T < TP, the magnetic (spin) susceptibility χ(T), and the relative infrared intensity of totally symmetric molecular modes. Exact thermodynamics of HCT for stacks up to N = 12 sites are applied to two CT salts with TP ∼ 50 and 120 K whose magnetism and infrare...