论文标题
在共轭聚合物中的热驱动偏振子传输
Thermally Driven Polaron Transport in Conjugated Polymers
论文作者
论文摘要
我们提出了在共轭聚合物中电荷 - 两极转运的杂化量子古典模拟。伴侣将其与单体的角旋转耦合，是通过时间依赖性的schrödinger方程来建模的，而单体则通过运动的运动方程进行经典处理。此外，通过假设单体受到Langevin方程建模的Brownian波动的影响，可以对系统进行热效。与单体旋转的电荷耦合将粒子定位在Landau极化子中，而单体的热波动会引起北极星动力学。该模型的紧急低能量表是极化重组能量，$ e_r $，因此$ t_r = e_r/k_b $是低温动态的方便量表。我们研究了两种类型的动力学 - 两者都与温度相关$ t <t_r $。在较低的温度状态下，系统保持在相同的准绝热状态，对应于无激活的极性扩散，因为北极子沿链随机爬行。然而，随着温度的升高，有一个越来越多的激活的转移过程，这与在绝热状态之间跳跃相对应。我们表明这些过程表现出Landau-Zener型动力学。我们注意到，由于我们的模型是一般的，它同样适用于共轭聚合物中的激子 - 孔子（即能量）传输，并在准单维分子堆栈中加电和激子极性转运。
We present a hybrid quantum-classical simulation of charge-polaron transport in conjugated polymers. The charge, which couples to the angular rotations of the monomers, is modeled via the time-dependent Schrödinger equation, while the monomers are treated classically via the Ehrenfest equations of motion. In addition, the system is thermalized by assuming that the monomers are subject to Brownian fluctuations modeled by the Langevin equation. Charge coupling to the monomer rotations localizes the particle into a Landau polaron, while the thermal fluctuations of the monomers causes polaron dynamics. The emergent low-energy scale of the model is the polaron reorganization energy, $E_r$, and thus $T_r = E_r/k_B$ is a convenient scale for the low-temperature dynamics. We investigate two types of dynamics -- both relevant for temperatures $T < T_r$. In the lower temperature regime the system remains in the same quasidiabatic state, corresponding to activationless polaron diffusion as the polaron crawls stochastically along the chain. As the temperature is raised, however, there is a cross-over to an additional activated transfer process which corresponds to hopping between diabatic states. We show that these processes exhibit Landau-Zener type dynamics. We note that as our model is general, it equally applies to exciton-polaron (i.e., energy) transport in conjugated polymers, and to charge and exciton polaron transport in quasi one-dimensional molecular stacks.
