※ 引述《rooket (rooket)》之铭言： : 　　今天读到phonon的部份 Kittel的第四章 : page 91, 要推导出第s层和上下层 displacement : 从 Hooke's law 开始 推出difference equation -Mw^2= C(u +u -2u ) : s+1 s-1 s : ( suppose u is dependent on time ) : 解出: : u = u*exp(isKa)exp(isKa)exp(iKa) : s+1 : u = u*exp(isKa)exp(isKa)exp(-iKa) : s-1 : where K is wavevector. : 我不知道如何从difference equation 推出 u ??? : 如果是 wave , 应该有 Kx-wt 这一项~~ 为何 u is indenpendent on x ? : 谢谢大家的解答~~ ︿(￣︶￣)︿ The concept of phonon is analogous to the photon of electromagnetic wave. Electromagnetic energy is quantized, so we come up with the concept of photon. But why the vibration of crystals is quantized ??? I think quantization come from constrained boundary conditions, then under what conditions wavevector K is quantized ?? I am very confused with the "phonon" .......... --

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