热涨落链中Holstein极化子的动力学
Dynamics of Holstein polaron in a chain with thermal fluctuations
摘要：
采用数值模拟的方法研究了在模拟环境温度$T$和恒定电场作用下，链中极化子在类Langevin微扰下的动力学行为.在半经典Holstein模型中，极化子在热力学平衡态的存在区域不仅与温度有关，而且与链长有关。因此，当我们从初始极化子数据计算动力学时，在相同温度下，不同长度的链的电荷质心的平均位移不同。对于一个大半径极化子，它是数值示出的“平均极化子位移”（只考虑极化子的峰值和它的位置）的行为类似于不同长度的链期间，当极化子持续的时间。极化子位移的类似斜率使人们能够找到极化子的平均速度，并通过与电荷迁移率类比，评估“极化子迁移率”。$T \approx 0$的极化子迁移率的计算值接近于在$T=0$的值，该值很小但不为零。对于小半径极化子对应的参数，动力学模拟显示了不动极化子和离域态之间的转换模式。新极化子的位置与前一个极化子的位置无关;电荷转移发生在离域态。
英文摘要：
Numerical modeling is used to investigate the dynamics of a polaron in a chain with small random Langevin-like perturbations which imitate the environmental temperature $T$ and under the influence of a constant electric field. In the semiclassical Holstein model the region of existence of polarons in the thermodynamic equilibrium state depends not only on temperature but also on the chain length. Therefore when we compute dynamics from initial polaron data, the mean displacement of the charge mass center differs for different-length chains at the same temperature. For a large radius polaron, it is shown numerically that the ``mean polaron displacement'' (which takes account only of the polaron peak and its position) behaves similarly for different-length chains during the time when the polaron persists. A similar slope of the polaron displacement enables one to find the polaron mean velocity and, by analogy with the charge mobility, assess the ``polaron mobility''. The calculated values of the polaron mobility for $T \approx 0$ are close to the value at $T=0$, which is small but not zero. For the parameters corresponding to the small radius polaron, simulations of dynamics demonstrate switching mode between immobile polaron and delocalized state. The position of the new polaron is not related to the position of the previous one; charge transfer occurs in the delocalized state.
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