ISSN:
0020-7608
Keywords:
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The ground states of eight molecules and some of their hole states are calculated. The calculations are performed on a medium-size home-made computer using self-written programs. The basis set used is LEMAO-3G, with scaling factors of the orbitals optimized by means of a method using orthogonal array and finding minima of fitted quadric curves. The conclusions are: (1) The LCAO-MO method is the reflection of the interference effect due to the wave nature of electrons. (2) The mathematical methods of rescaling the orbital exponents is the reflection of the orbital contraction or diffusion occurring during the formation of MO. These conclusions are in agreement with the Virial theorem and the variation principle. They are also strongly supported by the photoelectron spectroscopy data. The calculated values of the energies of the valence orbitals are very near to those obtained by using some extended basis set, which are reported to be very close to the Hartree-Fock limits. From these results and discussions it may be concluded that the nature of the covalent bond should be considered as an interplay and mutual conditioning between the wave nature of the electronic motion on the one hand and the various attractive and repulsive factors on the other hand, among which the kinetic energy should be a very important repulsive factor. The mutual screening effects of the electrons in various MOS, which are different for different molecules, are also very important. This is perhaps one of the main causes of the differences in properties of different molecules.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560230608
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