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This thesis is concerned with non-adiabatic effects in alkali/halogen collision systems. After a general survey of non-adiabatic molecular collision theory, and its application to such systems, calculations have been performed relating to three topics : (i) Vibrational energy distributions resulting from electron transfer collisions between alkali metal atoms and halogen molecules are often treated by the multi-curve crossing approach to the classical path approximation, in the form of two approximations, one valid at high collision energy, the other at low energy; the performance of these is evaluated over a wide energy range by comparison with the results from an "exact" multi-curve crossing approach. (ii) Classical trajectory calculations for reactive alkali / halogen collisions are performed using a simple ionic potential energy surface, developed earlier to model the weakening of the halogen bond by the metal ion immediately after the electron transfer. Detailed comparison is made between the results and those from experiment; good agreement is obtained for K/I₂ and comparison of the results for K/I₂ and Cs/I₂ indicates that this effect is not merely dependent on the charge of the ion. (iii) The population of ground and excited sodium atoms resulting from Na/I charge neutralisation collisions is investigated using the multi-curve crossing approach. Although it has been suggested that population inversions may be produced by such a process, it is shown that this is only possible at extremely high collision energies.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. Appendix: "Perturbation treatment of the ground state of H₂⁺" [by] William D. Lyon ... [et al.]: p. 115-120. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Abstracted in Dissertation abstracts, v. 17 (1957) no. 11, p. 2436. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 148).

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In this thesis calculations have been made with the Xα scattered wave (XαSW) and complete neglect of differential overlap (CNDO) methods. A common theme involves the parametrisation of the CNDO method for the heavier elements (e.g. atomic numbers greater than 10), although an initial study concerned the re-parametrisation of the CNDO method for systems based on LiF-, It is indicated that the conventional CNDO/2 parameters appear inadequate for ionic systems which involve substantial re-allocation of charge from the normal atomic states. For this application, the CHDO method was reparametrised by direct reference to a previously published near-Hartree-Fock calculation on diatomic LiF, and the suitability of the new CNDO parameters was assessed by calculations on (LiF)₂ and on clusters consisting of up 18 atoms. In independent calculations, Evarestov and Lovchikov (1977) showed these new parameters have advantages over the other sets when using CNDO-type calculations for investigating the band structure of LiF. Chapter 3 reports new XαSW calculations for some clusters formed by silver atoms; these are for Ag₇ and Ag₁₀. which simulate the (111) surface of silver, Ag₁₃ and Ag₁₉, which simulate bulk silver and two forms of Ag₇I which are designed to investigate the adsorption of iodine atoms on the (111) surface of silver. Local and total density of states curves are reported, and high coordinate atoms have been found to exhibit strong localisation OB the electronic structure. So far CNDO parametrisations are not well developed for So far CNDO parametrisations are not well developed for clusters of transition metal atoms, and in chapter 4 new CNDO parameters for silver have been obtained by comparing local and total density of states and charge distributions from CNDO calculations with those from the XαSW method for the Ag₇ cluster- The new CNDO parameters have then been used for making CNDO calculations on farther silver clusters, namely Ag₆, Ag₁₀, Ag₁₃ and Ag₁₉, and the results are compared with data from the XαSW calculations. These CNDO calculations give d-band widths in broad agreement with those from the XαSW method. The most significant difference is that the CNDO method gives less localisation on central atoms with high coordination numbers than is found from the XαSW calculations. It is suggested that this apparent deficiency of the CNDO calculations may be less serious when the clusters are being used for modelling part of a solid metal rather than for specifically investigating the properties of small metal particles. The final chapter of this thesis presents calculations on systems composed of the elements aluminium to sulphur. New calculations have been made with the XαSW method for the molecular clusters Al₇, Si₅H₁₂ and P₄, and comparisons made with experiment and with other calculations where possible. However the main reason for making these calculations has been to use the charge distributions and transition-state energies, along with information obtained previously by Salahub et al. for S₃, for deriving new CNDO parameters for the elements aluminium to sulphur. Calculations using these parameters have been tested against a new XαSW calculation made here for an Al₁₀ cluster (which simulates the (111) surface of aluminium), and against XαSW calculations made previously for P₈, P₄S₅, SiH₄, PH₃, H₂S and S0₂. This way of getting CNDO parameters seems broadly successful in these cases, and this work thereby provides a firmer basis for using results from XαSW calculations for extending the CNDO procedures systematically to a wider range of the heavier elements. / Science, Faculty of / Chemistry, Department of / Graduate

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1970. / Includes bibliographical references (leaves 327-332). / by John David Ramshaw. / Ph.D.

Thesis (Ph.D.)--McMaster University (Canada), 1990. / Source: Dissertation Abstracts International, Volume: 53-01, Section: B, page: 0301. Supervisor: R. F. W. Bader.

(i) Hydrogen Bonding Studies - The nature of hydrogen bonding in solutions of alcohols, ROH, in various solvents has been studied using nuclear resonance techniques. Data obtained from dilution-shift curves for the OH protons in alcohols have been combined with information derived from infra-red investigations of the OH stretching regions in these compounds. The information obtained has been interpreted in terms of three effects, (i) The electronic effects of the group R. (ii) The steric effects of the group R. (iii) Effects due to other forms of molecular association. On this basis, deductions have been made concerning the degree and type of association in these compounds. The relative hydrogen bonding strengths have been predicted in some instances. The importance of steric inhibition of hydrogen bonding by bulky substituent groups has also been demonstrated. Some dilution-shift studies of acrylic acid in various solvents have been carried out. Studies of the effect of temperature on the OH proton resonances of alcohols have led, amongst other things, to a value for the average hydrogen bond energy in a methanol / carbon tetrachloride solution. The temperature-shift curves for a variety of ortho-substituted phenols have also been obtained and discussed in the light of existing infra-red spectral evidence concerning the nature of hydrogen bonding in these substances. The relation between the association shifts and the integrated absorption intensities of alcohols has been discussed. A correlation between these two quantities was found for alcohols of a similar type. (ii) Studies of Unstable Positive Ions. (a) Triphenyl Carbonium Ions. The NMR spectra of a variety of substituted triphenyl carbonium ions in a trifluoroacetic acid trifluoroacetic anhydride solvent have been obtained at 40 Mc and 60 Mc. No unequivocal evidence as to the structures of these compounds has been obtained, i.e. no distinction between 'symmetrical propeller’ and assymetric forms was possible, due to the presence of exchange effects. The data have given information about the changes in electron density in the aromatic rings due to the various substituent groups. Partial assignments of the aromatic proton spectra have been given. The importance of hyperconjugative electron release by aliphatic substituents is indicated. Some preliminary investigations of the protonated form of 1,1-Di-p-anisylethylene have also been carried out. (b) The l⁺ Ion. The NMR spectra of solutions of iodine in oleum have been investigated to try and shed light on the possibility of the existence of the l⁺ ion in such systems. The measured broadenings and shifts of the oleum proton resonances at various iodine concentrations have been interpreted in terms of the presence of this species, which should be paramagnetic. A value for the magnetic moment of this ion has been obtained. Other evidence for the existence of the l⁺ ion has been fully discussed. / Science, Faculty of / Chemistry, Department of / Graduate