Due to the analogy with the hydrogen problem, the zero-density eigenstates are known analytically for any bulk semiconductor when excitations close to the bottom of the electronic bands are studied. In nanostructured materials, such as quantum wells, quantum wires, and quantum dots, the Coulomb-matrix element V k strongly deviates from the ideal two- and three-dimensional systems due to finite quantum confinement of electronic states. Hence, one cannot solve the zero-density Wannier equation analytically for those situations, but needs to resort to numerical eigenvalue solvers. In general, only numerical solutions are possible for all semiconductor cases when exciton states are solved within an excited matter. Further examples are shown in the context of the Elliott formula.