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# Molecular orbital theory for inorganic molecules

thesis

posted on 08.02.2017, 04:46 by Roby, Keith RaymondDuring the last decade, the concern of theoretical chemists has
rested largely with approximate calculations on organic molecules containing
n-electrons on the one hand, and with ab initio calculations on
very small molecules on the other. As a result of this work, together
with the development of large-scale computers, we are now in a position
to extend the vision in the direction of larger, inorganic molecules.
In terms of the investigation of experimental properties, the re-examination
of intuitive chemical concepts, and the formation of new concepts
to describe chemical bonding in a more rigorous way, the possibilities
of this development are enormous. There ought to be some important
implications for the theoretical chemist with respect to theoretical
methods, for the experimental chemist with respect to his understanding
and explanations of chemical behaviour, and for our knowledge of and
teaching about the chemical bond in general.
This thesis represents an examination of some of these possibilities.
Initially a critical review of ways and means of carrying out theoretical
calculations on inorganic systems is necessary. The conclusions drawn
from this review are used to consider two particular problem areas in
inorganic chemistry: the nature of the chemical bond in molecules containing
elements of the second row of the Periodic Table, especially the
sulphur-oxygen bond; and the electronic structure and experimental properties
of tetrahedral oxy-anions of the transition metals.
On the basis of its success in the areas of n-electron calculations
for organic molecules, ab initio calculations for small molecules, and
ligand field theory for transition metal complexes, together with the
large body of experience available about its use in calculations, the
molecular orbital theory is chosen as a framework for the methods
developed here. We now consider in detail the needs and requirements of
a theoretical approach to inorganic molecules, based on this theory.