The mathematics of the Hückel method is based on the Ritz method. In short, given a basis set of "n" normalized atomic orbitals formula_42, an "ansatz" molecular orbital formula_43 is written down, with normalization constant "N" and coefficients formula_44 which are to be determined. In other words, we are assuming that the molecular orbital (MO) can be written as a linear combination of atomic orbitals, a conceptually intuitive and convenient approximation (the linear combination of atomic orbitals or LCAO approximation). The variational theorem states that given an eigenvalue problem formula_45 with smallest eigenvalue formula_46 and corresponding wavefunction formula_47, any normalized trial wavefunction formula_48 (i.e., formula_49 holds) will satisfy