Hückel Molecular Orbital Theory

Abstract

This chapter includes the lowest level of computation of the Schrödinger equation, based on Hückel's molecular orbital theory. It covers topics such as the Born-Oppenheimer approximation, independent particle approximation, π-electron separation approximation, variational principle, the overlap integral, the Coulomb integral, the resonance integral, the secular matrix, and the solution to the secular matrix and chemical applications of the theory. The applications cover areas such as aromaticity, charge density calculation, stability and delocalization energy, spectrum, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), bond order, the free valence index, and electrophilic and nucleophilic substitution and the free-valence index. The real computation of the energy and wavefunction from the secular matrix has been included. A method to solve the secular matrix by finding the eigenvalues and eigenvectors has been illustrated with appropriate examples. AN Application of MATLAB in the computation process is also mentioned. A sufficient number of illustrative examples and exercises are included.