Spectroscopy is a study of the interaction between light and matter. As it was shown in the last two hundred years, the particular spectroscopic quantities can provide detailed information about the structure and properties of certain molecules or materials. This makes spectroscopy one of the most powerful approaches and far[1]reaching analysis tools in many fields of modern natural science.
Nowadays, spectroscopic techniques are becoming more and more complex, often focused on a specific non-linear property, and the interpretation of experimental data obtained from such sophisticated techniques is not straightforward. Indeed, with the increasing complexity of the experimental techniques, the intricacy of the experimental data has been rising proportionally. Therefore, the development of new spectroscopic techniques requires appropriate theoretical methods in order to provide a detailed interpretation of the investigated properties.
This thesis is mainly aimed at the development and implementation of new theoretical methods for the simulation of different spectroscopic effects in the ultraviolet-visible (UV-VIS) region, particularly One-photon Absorption (OPA), Electronic Circular Dichroism (ECD), Magnetic Circular Dichroism (MCD), and a number of others. All implementations were performed with a strong focus on applicability to organic molecules of increasing size. The implementations were performed in major scientific program packages (Turbomole and Q-Chem) in order to make them accessible to a broad scientific community. Another part of this thesis is devoted to extensive benchmark and critical comparison of existing computational protocols for the simulation of Transient Absorption (TA) in RNA and DNA bases, and it provides important insights for the interpretation of their TA spectra.