Abstract
In this research, a comprehensive study of dopamine was conducted using the theoretical first principles method due to its crucial importance as a hormone for the neurotransmission process in the animal body. Many basis sets and functionals were used for optimization of the compound to attain stability and find the appropriate energy point for the overall calculations. Then, the compound was doped with the first three members of the halogen family (fluorine, chlorine, and bromine) to analyze the effect of their presence in terms of change in their electronic properties, such as band gap and density of states, and spectroscopic parameters, such as nuclear magnetic resonance and Fourier transform infrared. It was found that the band gap of the system changes depending on the doping of halogens.