Conclusion

Abstract

In the work presented in the first Part of this thesis, we have used high-level electronic structure and nuclear quantum dynamics calculation techniques to study the photochemistry of simple aromatic organic molecules. In a first application, initiated during a six-month fellowship in the experimental group of Helen Fielding in the Chemistry Department of University College London, we have studied the photochemistry of aniline through a systematic exploration of the potential energy surfaces of the low-lying $1\pi \pi ^*$, $1\pi \sigma ^*$ and $2\pi \pi ^*$ states of the pmolecule using CASSCF and XMCQDPT2 calculations. Several previously unknown minimum energy conical intersections and the associated decay pathways have been reported. These include a prefulvene conical intersection between the $1\pi \pi ^*$ and the ground states, characterized by an out-of-plane distortion of the carbon atom of the phenyl ring holding the amino group.