Therefore, a commuting set consists of L 2 , one component of L (which is taken to be L z ) and H . The solution of the problem tells us that disregarding spin of the electrons, the set { H , L 2 , L z } forms a CSCO. Let | E n , l , m ⟩ ⟩ be any basis state in the Hilbert space of the hydrogenic atom. Then