Studies Of Mapped Discrete Variable Representation And Photo Detachment Mechanism Of Molecular Anion

In this dissertation, an improved FE-DVR representation was proposed which could be used in the time-dependent and independent quantum dynamics calculations. Based on the time-dependent quantum wavepacket theory, The photoelectron detachment of AuH2-, FH2- and their isotopic variants were studied. Spectroscopic features of the photoelectron spectra reveal a detailed picture of the electronic structure, rovibrational information about rovibrational states and transition state resonances for the neutral molecules.(1) We propose an optimized finite element discrete representation (OFE-DVR) method for solving the Schrodinger equation and representing the wavefunctions. The method is illustrated by calculations the eigenstates of one-dimensional Coulomb potential, the vibra-tional states of one-dimensional Morse potential, the two-dimensional Morse potential and the two-dimensional Henon-Heiles potential. The results were compared with the widely used Sinc-DVR, mapped Sinc-DVR and Mapped Fourier methods. The results suggest that the OFE-DVR method is much more efficient than the Sinc-DVR method, and is of comparable efficiency as the mapped Sinc-DVR method in finding vibrational states of one-dimensional Morse potential. Furthermore, the OFE-DVR method is particularly suitable for treating with atomic Coulomb singularity and expected to advance the study of electronic dynamics in quantum mechanics.(2) The photoelectron spectra of AuH2- and AuD2- anions were calculated. In order to simulate the photoelectron spectra of AuH2- and AuD2-, highly accurate ab initio PESs for both anionic and neutral AuH2 are constructed. Accurate quantum dynamics simulations based on these PESs are performed. The theoretical results provide a detailed intepretation for the experimental data. At the same time, the interpretation also sheds light on the rovibrational structures of AuH2 and AuD2. The stretching and bending modes of AuH2 and AuD2 at their equilibrium geometries suggested by the experimental and simulated spectra are in good consistent with each other.(3)The photoelectron spectra of FH2-, FD2- and FHD-anions were calculated. Two different methods are used to the simulate the spectra. The accurate quantum dynamics simulations, which are based on highly accurate new ab initio potential energy surfaces for both anionic and neutral FH2, were compared with all available experimental results. The results provide reliable interpretations for the experimental spectroscopic observations of the photoelectron spectra of FH2- and its isotopic variants. The latest high-resolution experimen-tal photoelectron spectra confirm the high accuracy of the CSZ potential energy surface for describing the resonance-enhanced reactivity of the neutral F+H2/D2/HD reaction.