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Title: Roatation-vibration states of triatomic molecules at dissociation
Author: Silva, B. C.
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2009
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Nuclear motion resonant states of triatomic molecules are calculated using an L2 method known as Complex Absorbing Potential (CAP). This method is implemented in a new program named RES3D which includes a new automatic procedure to obtain the resonant states’ energies and lifetimes, allowing for the first time the quantification of the results’ accuracy through a consistency test across different CAP functional forms. Its implementation is described in detail. Validation tests consisting of a comparison of HOCl resonances calculated with RES3D with those available in the literature, are presented. The largest calculations to date of the vibrational states of H+3 and D2H+ of all bound state eigenvectors and up to about 2000 cm−1 above dissociation are also presented. The results of these calculations are analysed through studies of the convergence of bound states, the calculation of relevant observables, and the visual analysis of wavefunctions. Based on eigenvectors obtained from these calculations, vibrational resonances for H+3 and D2H+, as well as H+3 at J = 3 are calculated with RES3D. D2H+ is used to study the resonances in multi-channel systems by investigating two energy regions: the one where D2 + H+ is the only dissociation product and the one where HD + D+ can also be formed. Branching ratios are obtained in the latter case by using different CAPs. It is shown that H+3 and D2H+ support narrow Feshbach-type resonances. The findings from the study of resonant states made using RES3D and possible technical improvements to the program are discussed. A brief description of the work currently being done to use RES3D in an attempt to fully characterise the spectrum of H2O is also presented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available