What is the Relation Between k and x in the Given Energy Function?

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SUMMARY

The discussion centers on the relationship between the wave vector \( k \) and the position variable \( x \) in the context of the energy function \( E = \frac{\hbar^2}{2m_e}k_x^2 + E_0(n_y^2 + 1) \). The energy function incorporates constants such as \( E_0 = \frac{\pi^2\hbar^2}{2m_eL_z} \) and is plotted over the interval \( x \in ]-L_z/2; L_z/2[ \). The user has attempted a Fourier transform to transition from position space to momentum space but seeks clarity on the direct relationship between \( k \) and \( x \).

PREREQUISITES
  • Understanding of quantum mechanics concepts, specifically wave functions and energy states.
  • Familiarity with Fourier transforms and their application in transitioning between position and momentum space.
  • Knowledge of the physical constants involved, such as \( \hbar \) (reduced Planck's constant) and \( m_e \) (electron mass).
  • Basic proficiency in plotting functions and interpreting graphical data in physics.
NEXT STEPS
  • Research the implications of Fourier transforms in quantum mechanics, focusing on the relationship between position and momentum.
  • Study the concept of wave vectors and their physical significance in quantum systems.
  • Explore the mathematical derivation of energy functions in quantum mechanics, particularly in relation to boundary conditions.
  • Learn how to effectively plot energy functions in both position and momentum space using tools like Python's Matplotlib.
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Students of quantum mechanics, physicists exploring wave-particle duality, and anyone involved in computational physics or energy function analysis.

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Homework Statement


I have an energy function as follows:
E = \dfrac{\hbar^2}{2m_e}k_x^2+E_0\left(n_y^2+1\right)
Where E_0 = \dfrac{\pi^2\hbar^2}{2m_eL_z}
I am asked to plot this energy for x\in ]-L_z/2;L_z/2[
I know everything but not the relation between k and x?.

The Attempt at a Solution


I Fourier transform the energy from x to k-space(momentum space) and get some dela functions in k multiplied on as one would expect, but this seems odd to me and I want to know:
What is the relation between k and x?
 
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Follow up:
Maybe I shall choose some k and just plot a constant, but it seems silly.
 

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