# Homework Help: Solid State - Energy(position)

1. Nov 6, 2012

### dikmikkel

1. The problem statement, all variables and given/known data
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?.

3. 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?

2. Nov 6, 2012