If you solve the Time Independent Schrodinger equation for the Harmonic Oscillator, that is
-\frac{\hbar^2}{2m} \frac{d^2\Psi}{dx^2} + \frac{1}{2}kx^2 \Psi = E \Psi
The quantization of energy comes from the boundary conditions (ie, \Psi = 0 when x= \infty or x = -\infty).
I would like to know how to calculate the ##[\hat{H}, \hat{P}]## for a particle in a 1D box? At the first glance it seems that they commute but they don't get diagonalized in identical basis. How to calculate this commutation?
I don't know why the electrons in atoms are considered in the orbitals while they could be in sates which are superpositions of these orbitals? If electrons are in the superposition of these orbitals their energy expectation value is also constant, and the atom seems to be stable!