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Mathcad in the Chemistry Curriculum
Theresa Julia Zielinski Monmouth University West Long Branch, NJ 07764-1898
Student Access to Symbolic Mathematics Software
Hückel Theory I and II: HucI_2001.mcd, HucII_2001.mcd, HucI_8.mcd, HucII_8.mcd, HucI.pdf, HucII.pdf James M. LoBue, Department of Chemistry, Georgia Southern University, P. O. Box 8064, Statesboro, GA 30460;
[email protected] The focus of Hückel theory in the chemistry curriculum is usually the determination of the orbitals and energy levels of a conjugated system. Students are then able to learn the basic analysis of a simple orbital problem. Using the linear algebra functions available in Mathcad, it is now possible to describe, almost completely, the process that results in orbitals and levels. All that is lacking is an exploration of the algorithm for matrix diagonalization. The Hückel I and II Mathcad documents provide a review of, or perhaps an introduction to, the Heisenberg formulation of quantum mechanics. Therefore, these pages are geared toward the advanced undergraduate, the beginning graduate student, or even the talented junior chemistry major. Described in Hückel I is an introduction to the method of generating Hückel Theory results along with an introduc-
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tion to applications like HOMO-LUMO transition energy and the prediction of nucleophilic and electrophilic substitution. Hückel II treats more sophisticated topics like the generation of partial charges, bond orders, and the determination of aromatic character. Since these topics have ab-initio analogs, Hückel I and II provide a “hands-on” introduction to important aspects of computational chemistry as well. The development found in Hückel I and II could easily be extended to molecules with heteroatoms and it is expected that other workers will find further extensions.
Figure 3. Hückel energy level diagram and molecular orbital energies for benzene.
Journal of Chemical Education • Vol. 79 No.11 November 2002 • JChemEd.chem.wisc.edu
