ISSN:
0020-7608
Schlagwort(e):
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The concepts underlying the definition of bond energies in terms of potentials at the nuclei are outlined. The theory is rooted, first, in a definition of the energy, Ei, of “atom” i in the molecule in terms of the potential energy, V(i, mol), of nucleus Zi in the field of all the electrons and nuclei of the molecule: Ei = Kimol V(i, mol). The Kimol parameter, which is not required to be a constant in the derivation of the energy expression describing the contribution of an ij bond, turns out to be virtually constant for each atomic species - a situation which is exploited in numerical applications. Second, the Hellmann - Feynman theorem is applied in the calculation of the derivative, δΔEa*/δZi, of the atomization energy, ΔEa*, using (i) the exact quantum-chemical definition of ΔEa* and (ii) the view that ΔEa* is the sum of bond energy contributions, εij, plus a small interaction between nonbonded atoms. The individual bond energies derived in this manner necessarily depend on local charges at the bond-forming atoms. Numerical applications illustrate how this new bond-energy formula provides a simple link between typical saturated, olefinic, acetylenic, and aromatic hydrocarbons.
Zusätzliches Material:
4 Tab.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/qua.560260514
