论文标题
核运动在电子的量子运输中的非绝热作用：一项自一致的Keldysh-Langevin研究
Non-Adiabatic Effects of Nuclear Motion in Quantum Transport of Electrons: A Self-Consistent Keldysh-Langevin Study
论文作者
论文摘要
分子连接几何形状是根据嵌入非平衡电子的随机量子环境中的核自由度来建模的。分子几何形状的时间进化是通过平均力，摩擦力和随机力来控制的，这些力是由许多电子在连接处隧穿而产生的，以实现给定的核振动。相反，电流驱动的核动力学会反馈到电子电流，可以根据对经典核速度和加速度具有明确依赖性的电流的扩展表达式捕获。电流诱导的核力量和非绝热电流是通过Wigner空间中的Keldysh-Kadanoff-Baym方程的时间尺度分离解决方案计算出的非平衡绿色功能。将该理论应用于分子连接，表明当核运动被认为是非平衡时，非绝热校正起着重要作用，尤其是表明核运动的非平衡和平衡描述产生明显不同的当前特征。可以观察到，非平衡描述通常相对于平衡描述产生增强的电导曲线，并提供了有效温度是稳态特性的有效度量的证据。最后，我们观察到，核运动的非平衡描述可以通过与不均匀温度曲线结合的多米尼马势能表面的出现来引起陆地的大灯效应。探索了Landauer的大灯效应及其对当前特征，等待时间和Fano因子的影响，以获得有效的绝热潜力，即单个，双重和三重电位在电压的函数之间变形。
The molecular junction geometry is modelled in terms of nuclear degrees of freedom that are embedded in a stochastic quantum environment of non-equilibrium electrons. Time-evolution of the molecular geometry is governed via a mean force, a frictional force and a stochastic force, forces arising from many electrons tunnelling across the junction for a given nuclear vibration. Conversely, the current-driven nuclear dynamics feed back to the electronic current, which can be captured according extended expressions for the current that have explicit dependencies on classical nuclear velocities and accelerations. Current-induced nuclear forces and the non-adiabatic electric current are computed using non-equilibrium Green's functions via a time-scale separation solution of Keldysh-Kadanoff-Baym equations in Wigner space. Applying the theory to molecular junctions demonstrated that non-adiabatic corrections play an important role when nuclear motion is considered non-equilibrium and, in particular, showed that non-equilibrium and equilibrium descriptions of nuclear motion produce significantly different current characteristics. It is observed that non-equilibrium descriptions generally produce heightened conductance profiles relative to the equilibrium descriptions and provide evidence that the effective temperature is an effective measure of the steady-state characteristics. Finally, we observe that non-equilibrium descriptions of nuclear motion can give rise to the Landauer blowtorch effect via the emergence of multi-minima potential energy surfaces in conjunction with non-uniform temperature profiles. The Landauer blowtorch effect and its impact on the current characteristics, waiting times and the Fano factor are explored for an effective adiabatic potential that morphs between a single, double and triple potential as a function of voltage.
