Hückel molecular orbital (HMO) theory
The simplest molecular orbital
theory of π-conjugated molecular systems. It uses the following approximations: π-electron
representation of the π-molecular orbitals; neglect of electron-electron and nuclear-nuclear
repulsions (in fact, the assumption that these cancel). The diagonal elements of the
effective Hamiltonian, coulombic integrals, and the off-diagonal elements, resonance
integrals, (accounted for only directly bonded atoms) are chosen as empirical parameters,
all overlap integrals being neglected.