"Quantum scattering"의 두 판 사이의 차이

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14번째 줄: 14번째 줄:
 
<h5>continuous spectrum</h5>
 
<h5>continuous spectrum</h5>
  
* e^{ikx} represents a wave traveling to the right, and e^{−ikx} one traveling to the left.
+
* e^{ikx} represents a wave traveling to the right, and e^{−ikx} one traveling to the left
* <math>a(k)e^{-ikx}+b(k)e^{ikx}</math>
+
* e^{−ikx} is incoming wave from the right to the left
* a(k) transmission coefficient
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* reflection and transmission coefficient<br><math>\varphi \sim e^{-ikx}+\rho(k,t)e^{ikx}</math> as <math>x\to +\infty</math><br><math>\varphi \sim \tau(k,t)e^{-ikx}</math> as <math>x\to -\infty</math><br><math>\rho(k,t)</math> and <math>\tau(k,t)</math> are called the reflection and transmission coefficient<br>
* b(k) reflection coefficient
 
 
 
<math>\varphi \sim e^{-ikx}+\rho(k,t)e^{ikx}</math> as <math>x\to +\infty</math>
 
 
 
<math>\varphi \sim \tau(k,t)e^{-ikx}</math> as <math>x\to -\infty</math>
 
 
 
<math>\rho(k,t)</math> and <math>\tau(k,t)</math> are called the reflection and transmission coefficient
 
  
 
 
 
 
32번째 줄: 25번째 줄:
  
 
* [[Schrodinger equation]]<br><math>E \psi = -\frac{\hbar^2}{2m}{\partial^2 \psi \over \partial x^2} + V(x)\psi</math><br>
 
* [[Schrodinger equation]]<br><math>E \psi = -\frac{\hbar^2}{2m}{\partial^2 \psi \over \partial x^2} + V(x)\psi</math><br>
* <math>\varphi_{xx}+(\lambda-u)\varphi=0</math>
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* simplified form<br><math>-\varphi_{xx}+u(x)\varphi = \lambda\varphi</math><br>  <br><math>\varphi_{xx}+(\lambda-u(x))\varphi=0</math><br>  <br>
  
 
 
 
 
  
 
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<h5>delta potential example</h5>
  
<h5>delta potential</h5>
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<math>V(x) = \lambda\delta(x)</math>
  
 
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<math>\psi(x) = \begin{cases} \psi_{\mathrm L}(x) = A_{\mathrm r}e^{ikx} + A_{\mathrm l}e^{-ikx}, & \text{ if } x<0; \\ \psi_{\mathrm R}(x) = B_{\mathrm r}e^{ikx} + B_{\mathrm l}e^{-ikx}, & \text{ if } x>0, \end{cases}</math>
 
 
 
 
  
 
 
 
 

2011년 2월 8일 (화) 12:37 판

introduction

 

 

 

continuous spectrum
  • e^{ikx} represents a wave traveling to the right, and e^{−ikx} one traveling to the left
  • e^{−ikx} is incoming wave from the right to the left
  • reflection and transmission coefficient
    \(\varphi \sim e^{-ikx}+\rho(k,t)e^{ikx}\) as \(x\to +\infty\)
    \(\varphi \sim \tau(k,t)e^{-ikx}\) as \(x\to -\infty\)
    \(\rho(k,t)\) and \(\tau(k,t)\) are called the reflection and transmission coefficient

 

 

time independent Schrodinger equation
  • Schrodinger equation
    \(E \psi = -\frac{\hbar^2}{2m}{\partial^2 \psi \over \partial x^2} + V(x)\psi\)
  • simplified form
    \(-\varphi_{xx}+u(x)\varphi = \lambda\varphi\)
     
    \(\varphi_{xx}+(\lambda-u(x))\varphi=0\)
     

 

delta potential example

\(V(x) = \lambda\delta(x)\)

\(\psi(x) = \begin{cases} \psi_{\mathrm L}(x) = A_{\mathrm r}e^{ikx} + A_{\mathrm l}e^{-ikx}, & \text{ if } x<0; \\ \psi_{\mathrm R}(x) = B_{\mathrm r}e^{ikx} + B_{\mathrm l}e^{-ikx}, & \text{ if } x>0, \end{cases}\)

 

harmonic oscillator

 

 

example
  1. \[Lambda] := -1
    u[x_] := -2 Sech[x]^2
    f[x_] := Sech[x]
    Simplify[D[D[f[x], x], x] + (\[Lambda] - u[x]) f[x]]
    Plot[u[x], {x, -5, 5}]

 

 

 

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