Student handout: Quantum Calculations on the Hydrogen Atom

Central Forces 2021

Students are asked to find eigenvalues, probabilities, and expectation values for \(H\), \(L^2\), and \(L_z\) for a superposition of \(\vert n \ell m \rangle\) states. This can be done on small whiteboards or with the students working in groups on large whiteboards.

Students then work together in small groups to find the matrices that correspond to \(H\), \(L^2\), and \(L_z\) and to redo \(\langle E\rangle\) in matrix notation.

What students learn
  • Eigenvalues and eigenstates
  • Measurements of energy and angular momentum for hydrogen atom
  • Quantum probabilities
  • Superposition of states
  • New degeneracies

For the state \[ \left|{\Psi}\right\rangle = \sqrt{\frac{7}{10}} |2, 1, 0\rangle + \sqrt{\frac{1}{10}} |3, 2, 1\rangle + i\sqrt{\frac{2}{10}} |3, 1, 1\rangle\]

Calculate

  • \(\mathcal{P}(L_z=\hbar)\)
  • \(\langle L_z\rangle\)

    Then, if you have time, continue with these calculations:

  • \(\mathcal{P}(L^2=2\hbar^2)\)
  • \(\langle L^2\rangle\)
  • \(\mathcal{P}(E=-13.6eV/3^2=-1.51eV)\)
  • \(\langle E\rangle\)
  • What measurements can be degenerate on the Hydrogen atom?


Keywords
Probabilities Expectation Value Hydrogen Hydrogen Atom Degeneracy Kets
Learning Outcomes