※ 引述《rooket (rooket)》之銘言： : 　　今天讀到phonon的部份 Kittel的第四章 : page 91, 要推導出第s層和上下層 displacement : 從 Hooke's law 開始 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. : 我不知道如何從difference equation 推出 u ??? : 如果是 wave , 應該有 Kx-wt 這一項~~ 為何 u is indenpendent on x ? : 謝謝大家的解答~~ ︿(￣︶￣)︿ 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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