Theoretical calculation of bandstructure and spectroscopic analysis of complex molecular systems

Complex molecules (TNT, cytosine, ascorbic acid, dopamine, and diphenhydramine) are important antioxidant agent that act as an electron donor and is involved in many physiological process. Structural modification in complex molecules is subject of extensive biochemical research due to its involvement in a variety of relevant phenomena including electron transport, complex redox reactions, neurochemical reactions, enzymatic reactions, and chemotherapeutic potentials. In this work, the structure of complex molecules is modified via doping with first three members of halogen and alkali-earth metals to investigate the changes in the electronic structure and spectroscopic parameters using first principle methods. To obtain the lowest energy strcutures, different basis sets in density functional theory (DFT) and Hatree-Fock approaches ere employed in the geometry optimization process. The potential energy maps of the strucutres were computed to study the molecular orientations and their optical and electrical properties. The spectroscopic properties were computed via UV-vis and nuclear magnetic resonance (NMR) spectroscopies to study the effects of doping into the complex molecules. To obtain the further insights into the chemical structure, the fourier transform infrared (FT-IR) spectra of the materials were theoretically investigated. It was found that the bandgap is sensitive to doping as we moved from to chlorine to bromine in the halogen group and the same effect in the alkaline-earth metals from lithium to sodium