Finding Eigenvalues by Diagonalization

By substituting back into the definition of a , we get the solution set for the energy spectrum Ei. In ethylene there are two elements on the diagonal, xu and X22, leading to Ei and 2- In larger conjugated n systems, there will be more. 

If dropping x as is usually said, sounds a little arbitrary to you (it does to me, too), what we are really doing is concentr ating on one term of a sum 

Polynomial root finding, as in the previous section, has some technical pitfalls that one would like to avoid. It is easier to write reliable software for matrix diagonalization (QMOBAS, TMOBAS) than it is for polynomial root finding hence, diagonalization is the method of choice for Huckel calculations. 

---