On the calculation of the energy in unsaturated hydrocarbon molecules

Abstract

It frequently happens that we wish to evaluate the total energy of the mobile, or π, electrons in an unsaturated hydrocarbon molecule. According to the method of molecular orbitals(1) this energy is the sum of individual electronic energies ∊r, and the summation is over all the occupied orbitals. The energies ∊r are the roots of the secular determinant, and, if we writeand suppose that there are n unsaturated carbon atoms, then the equation that gives the energies zr is