Commutator rules:
The harmonic oscillator Hamiltonian is
The energy of a harmonic oscillator is
where 
.
The energy of a rigid rotor is given by
The energy levels of a hydrogenic atom are given by
with
The 1s wavefunction of a hydrogenic atom is
where the Bohr radius 
is given by
In spherical polar coordinates, 
. The coordinates 
and 
run over the following ranges: 
, 
.
Conversions:
Recommended values of fundamental constants:
