Charge Order and Photoinduced Nonlinear Dynamics in Low-Dimensional Molecular Conductors

在(DCNQI)2Cu中，导电性和磁性通过π和d轨道的杂化联系在一起。在高压下的绝缘体相中，三重晶格变形和顺磁性并存。Peierls和Mott机制协同工作。即使这些轨道之间的能级差并不是最优的，也会发生自掺杂来稳定这个晶格扭曲的相。两带Peierls-Hubbard模型的精确对角化研究证明了这一事实。在有机电荷转移络合物TTF-CA中，在低温或高压下发生了从顺电中性相到铁电离子相的转变。光激发也会触发这种转变。对于具有交变势的扩展Peierls-Hubbard模型，求解了含时薛定谔方程。研究了离子相电荷密度和晶格位移的动力学，以再现光激发强度的阈值。Time-…的傅里叶分析更多的依赖离子性阐明了激子的快速运动、慢的晶格振动和更慢的中性离子磁区边界的集体运动。光激发产生与初始极化相反的离子磁区，晶格有序迅速衰减。这与二次谐波的演化快于光反射率是一致的。在卤素桥联的双核金属络合物中，根据配体、卤素离子和反离子的不同，会出现不同的电荷有序相和晶格有序相。在Peierls-Hubbard模型中研究了各电子相的形成机制。尤其是碘、铂和配体POP、卤离子和反离子。碘、铂和配体的作用机理，存在电荷密度波(CDW)和电荷极化(CP)相。磁滞回线中的光激发触发了一个过渡相，在低能下不会在双核单元之间转移电荷，即使在高能下也不会生长CDW核。较少

In (DCNQI)_2Cu, conductivity and magnetism are correlated through hybridization of π and d orbitals. In the insulator phase under high pressure, three-fold lattice distortion and paramagnetism coexist. Peierls and Mott mechanisms work cooperatively. Even the level difference between these orbitals is not optimal, self-doping takes place to stabilize this lattice-distorted phase. This fact is demonstrated by the exact diagonalization studies for a two-band Peierls-Hubbard model.In organic charge-transfer complex, TTF-CA, a transition takes place from the paraelectric neutral phase to the ferroelectric ionic phase at a low temperature or under high pressure. Photoexcitation also triggers the transition. The time-dependent Schrodinger equation is solved for an extended Peierls-Hubbard model with alternating potentials. Dynamics of charge density and lattice displacements from the ionic phase is studied to reproduce a threshold in phtoexcitation intensity. The Fourier analysis of the time- … More dependent ionicity clarifies the fast excitonic motion, the slow lattice vibration, and the even slower collective motion of neutral-ionic domain boundaries. Photoexcitation produces ionic domains with the opposite polarization to the initial one, by which the lattice order quickly decays. This is consistent with the faster evolution of the second harmonic generation than the photoreflectivity.In halogen-bridged binuclear metal complexes, various charge- and lattice-ordered phases appear depending on the ligand, halogen ion, and counter ion. The mechanisms of the respective electronic phases are investigated in Peierls-Hubbard models. Especially with iodine, platinum, and ligand pop, halogen ion, and counter ion. The mechanisms of the iodine, platinum, and ligand pop, there appear charge-density-wave (CDW) and chargepolarization (CP) phases. Photoexcitation within the hysteresis loop triggers a transition phase does not transfer charge among binuclear units at low energies, and does not grow CDW nuclei even at high energies. Less