窄隙和空间织构下的波包输运理论：非绝热性和半经典性
Theory of wavepacket transport under narrow gaps and spatial textures: non-adiabaticity and semiclassicality
摘要：
我们概括了著名的半经典波包方法从绝热到非绝热制度。对于具有空间变化的能带结构的系统，特别需要覆盖这两种状态的统一描述，其中同时存在各种尺寸的带隙，例如以莫尔图案存在。对于一个单一的波包，替代以前的推导拉格朗日变分法，我们表明，相同的半经典运动方程可以通过引入类似的Eklfest定理的空间纹理诱导力算子。对于半经典计算的电流，系综的波包绝热动力学的基础上示出，以及对应的相空间流体的流体的质量和速度是两个可区分的属性。这种区别并不遗传到具有非绝热动力学的波包系综。我们将绝热动力学理论推广到非绝热区域，考虑到退相干，退相干与电场的共同作用有利于某种形式的带间相干。稳态密度矩阵作为相空间变量的函数，然后获得唯象计算的传输电流。该结果适用于有限电场，通过将电场取为无穷小，从而再现了已知的绝热极限，从而获得了从绝热到非绝热情况的统一描述。
英文摘要：
We generalise the celebrated semiclassical wavepacket approach from the adiabatic to the non-adiabatic regime. A unified description covering both of these regimes is particularly desired for systems with spatially varying band structures where band gaps of various sizes are simultaneously present, e.g. in moiré patterns. For a single wavepacket, alternative to the previous derivation by Lagrangian variational approach, we show that the same semiclassical equations of motion can be obtained by introducing a spatial-texture-induced force operator similar to the Ehrenfest theorem. For semiclassically computing the current, the ensemble of wavepackets based on adiabatic dynamics is shown to well correspond to a phase-space fluid for which the fluid's mass and velocity are two distinguishable properties. This distinction is not inherited to the ensemble of wavepackets with the non-adiabatic dynamics. We extend the adiabatic kinetic theory to the non-adiabatic regime by taking into account decoherence, whose joint action with electric field favours certain form of inter-band coherence. The steady-state density matrix as a function of the phase-space variables is then phenomenologically obtained for calculating the transport current. The result, applicable with a finite electric field, expectedly reproduces the known adiabatic limit by taking the electric field to be infinitesimal, and therefore attains a unified description from the adiabatic to the non-adiabatic situations.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
