The quantum mechanical wavefunctions and energies (eigenvalues) are found by solving the Schrödinger equation with this Hamiltonian. Due to the spherical symmetry of the system, it is natural to use spherical coordinates r {\displaystyle r} , θ {\displaystyle \theta } and ϕ {\displaystyle \phi } . When this is done, the time-independent Schrödinger equation for the system is separable, allowing the angular problems to be dealt with easily, and leaving an ordinary differential equation in r {\displaystyle r} to determine the energies for the particular potential V ( r ) {\displaystyle V(r)} under discussion.