This Thesis contains the results obtained using correlated <i>ab initio</i> calculations for both the ground and excited states of a series of triatomic molecules, such as ozone (O<sub>3</sub>) and the halogen oxides (X<sub>2</sub>O, where X = F, CI, Br and I), together with a subset of the pseudo halogens, including fluorine, chlorine, bromine and iodine azide, isocyanate and isothiocyanate. Chapter 1 presents a summary of the methods used to carry out these calculations, starting with the Schrödinger equation and the methods used to solve it, and proceeding to the discussion of differing methodologies such as SCF, multi-configuration SCF and CASSCF, CI and MP2 methods. Chapter 2 describes some of the ground state properties calculated in this work, in quantum chemical terminology, as well as discussing some of the differences in values obtained by experimental and theoretical methods. Chapters 3 and 4 are concerned with the studies on the ozone molecule, with the former covering the ground state and its properties, and the latter presenting the results for the excited states. Chapter 4 includes a comparison with the experimental UV and VUV spectra in the 0 to 12eV region, and assignments are offered for the valence and Rydberg states found in this energy range. These results suggest that the number of states presently identified by spectroscopic means are well short of those that might be expected in the energy range. Chapters 5 describes the study of a subset of the pseudo halogens. These results are concerned solely with the ground state and molecular properties relating to the wave-function as well as structural and ground state spectra such as infrared spectra; where possible these calculated results have been compared with experimental data. The final two Chapter 6 and 7, are devoted to the X<sub>2</sub>O molecules, where X = F, Cl, Br and I. Chapter 6 discusses the ground state properties of the molecules and compares with experiment where such data is known, and predicts the structure and properties of I<sub>2</sub>O. The final Chapter covers the excited states of the X<sub>2</sub>O molecules, where just the cases where X = F, Cl and Br are examined. Theoretical UV+VUV spectra produced, for each molecule, and Cl<sub>2</sub>O has been compared with the experimental data.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:659916 |
| Date | January 2002 |
| Creators | Nelson, Alistair David |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15497 |
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