Ab initio simulations of vibrational and electronic structure evaluated against K-edge resonant inelastic X-ray scattering

Abstract: The work of this thesis is focused on investigation of electronic and molecular structure and dynamics a molecular species in solutions and minerals in relation to resonant inelastic X-ray scattering (RIXS). The studies have been carried out by means of quantum chemistry calculations using density functional theory (DFT) and multi-configurational methods and quantum dynamics simulations using wave packet dynamics and ab initio molecular dynamics. By applications of these computational tools, I have studied the ultra-fast core-excited state dynamics and the RIXS process. With theoretical spectrum simulations, we can analyse the vibrational information of RIXS.The aim of these investigations is to probe the local electronic structure of ammonia and the hydroxyl group and their chemical interactions with the environment, e.g. hydrogen bonding, in liquid and solid state molecular systems. In Paper I, DFT calculations and wave packet dynamics has been used to simulate the O K-edge X-ray absorption (XAS) spectra and RIXS spectra to investigate the local vibrational structure of the hydroxyl groups of the kaolinite crystal. In Paper II, the N K-edge XAS, XES and RIXS spectra are simulated by application of DFT and multi-configurational methods combined with ab initio molecular dynamics with the aim to study the hydrogen bonding environment of aqueous NH3.