Branchett, Susan Elizabeth; (1991) Bound and continuum states of diatomic molecules using the R-matrix method. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Calculations are presented for electronic excitation of H2 by electron impact. For the initial calculations, ah initio R-matrix scattering techniques are used to represent scattering from the ground to five low lying electronic states of H2. Each target state is represented by a full configuration interaction treatment within a basis of Slater type orbitals, optimised to give accurate vertical excitation energies. All total symmetries including 2φg are included in the scattering calculation. Eigenphase sums and integral cross sections are presented for this model together with assignments of the resonance structures produced. This model is then extended to include the lowest seven electronic states of H2 at the equilibrium geometry. Eigenphase sums and resonance feature analysis are presented for excitation from the ground to the six excited states included in the calculation. Integral cross sections are also presented for these processes and extensive comparison made with experimental data. Differential cross sections calculated using the seven state model are presented for both resonant and non-resonant energy regions and comparison made with previous experimental and theoretical results. A method of adapting scattering calculations to calculate bound states of molecules within the R-matrix method is presented. This method is based on atomic method of Seaton (1985). The results of test calculations on the bound states oi CH and HeH, at fixed internuclear separation, are presented together with results for the vibrational bound states of HeH. The development of this method made it possible to calculate transition dipoles for excitation processes. Results for the transitions dipoles of H2, as a function of internuclear separation, are presented and comparison made with available theoretical data.

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