| Extended Huckel Method |
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| CATEGORIES ABOUT EXTENDED HUCKEL METHOD | |
| semiempirical quantum chemistry methods | |
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It is common in many theoretical studies to use the extended Huckel molecular orbitals as a preliminary step to determining the molecular orbitals by a more sophisticated method such as the CNDO/2 method and Ab Initio Quantum Chemical methods. This leads to the determination of more accurate structures and electronic properties. The method was first used by Roald Hoffmann who developed, with Robert Burns Woodward , rules for elucidating Reaction Mechanism s (the Woodward-Hoffmann Rules ). He used pictures of the molecular orbitals from extended Huckel theory to work out the orbital interactions in these cycloaddition reactions. A closely similar method was used earlier by William Lipscomb for studies of boron hydrides and a related method has been used for studies of other inorganic molecules. The method works poorly for molcules that contain atoms of very different Electronegativity . To overcome this weakness, several groups have suggested iterative schemes that depend on the atomic charge. One such method, that is still widely used in Inorganic and Organometallic chemistry is the Fenske-Hall method. REFERENCE Hoffmann, R., ''Journal of Chemical Physics'', 39, 1397 (1963). Hall, M. B. and Fenske, R. F., ''Inorganic Chemistry'', 11, 768 (1962) SEE ALSO |
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