Properties and applications of the average interparticle distance
The first and second moment operators are used to define the origin invariant shape and size of a molecule or functional group, as well as expressions for the distance between two electrons and the distance between an electron and a nucleus. The measure of molecular size correlates quite well with an existing theoretical measure of molecular volume calculated from isodensity contours. Also, the measure of size is effective in predicting steric effects of substituents which have been measured experimentally. The electron-electron and electron-nuclear distances are related to components of the Hartree-Fock energy. The average distance between two-electrons can model the Coulomb energy quite well, especially in the case of localized molecular orbitals. The average distance between an electron and a nucleus is closely related to the electron-nuclear attraction energy of a molecule.
A relationship between the sizes and energies of localized molecular orbitals. I. A study of selected first‐row hydrides
Ab initio calculations have been performed on selected first-row hydrides with a large Gaussian basis set. Energy localized molecular orbitals (LMO'S) were computed and analysed in terms of their sizes and shapes. The total molecular electronic energy was partitioned into components which may be associated with an MO, and the relationship between the sizes and energies of such orbitals was examined. It was found that a simple energy–size relationship exists for core LMO'S but only approximately holds for bond LMO'S.
Wave mechanics : the first fifty years
The topics discussed are the beginnings of chemical physics and wave mechnnics, the development of quantum mechanics during 1924 to 1926, central fields in two vis-a-vis three dimensions, quantum theory of valence, the localization of electrons and the chemical bond, wave mechanical treatment of hydrogen bonded systems, hybrid bond orbitals, wave mechanics for the electronic structure of molecules through configuration interaction, spin and Pauli principle, time-dependent Hartree -- Fock theory for atomic properties, wave mechanics effects on inorganic chemistry, and ligand fields, also group theoretic view of weakly interacting sites, role of symmetry and spin restrictions in reactive and nonreactive collisions and molecular decompositions, the role of semi-empirical SCF MO methods, the influence of wave mechanics on organic chemistry, quantum biochemistry, wave mechanics for natural optical activity in organic molecules, photoelectron spectroscopy and the electronic structure of matter, electronic structures of complex molecules and solids determination, density matrix methods in x-ray scattering and momentum space calculations, and an approach to quantum theory are covered. (JFP)