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【摘要】大多数固体物理教材,对布洛赫电子半经典模型的阐述,存在一些有争议的概念。如“速度算符”、“波包模型”﹑对运动学方程的理解等。本文逐一指出这些问题。首先量子力学没有速度概念,也没有唯一的速度算符,但是可以利用一些定义来求速度的平均值,而速度算符的说法是不妥的;此外,德布罗意波包因为色散而变形,不能用以表示布洛赫电子;最后,对于布洛赫电子运动学方程,也指出在外场作用下原初量子化图像被破坏时它的运用限制。 【关键词】布洛赫电子;半经典模型;“速度算符”;波包;运动学方程
[Abstract] In the most textbooks of Solidstate Physics, there are several incorrect concepts on the semiclassical model of Bloch electrons. Such as: “velocity operator”、 “wave packet model”、and explanation of kinetic equation, which are pointed out one by one. Firstly, there is no velocity concept in Quantum Mechanics and no unique velocity operator, but gotten the expectation values by different definitions; Secondly, the wave packet with distortion is not the representation of Bloch electrons. Finally, the limitation of the kinetic equation in the electromagnetic fields is expressed. [Key words] Bloch electrons; Semiclassical model; “Velocity operator”; Wave packet model; Kinetics equation. |