Figure shows the conventional calculation of a spectral feature (absorption spectrum, density of states, etc.) where the electronic states are simply ordered by their energies. The resulting composition of the first peak in the spectrum is a mixture of two electronic states with different characters. When the analysis in the basis of the reference states as proposed here is introduced, the excited states become ordered by their character, see Figure . The spectral features are now comprised only of excited states with the same character. In this way, the true distribution of the density of a single electronic state (or any other property) along the energy axis can be extracted from a nuclear ensemble.