The article provides an overview of the application of density functional theory (DFT) in bioinorganic chemistry, particularly in the modeling of structures, properties, and processes related to photosynthesis. DFT has become a valuable tool for validating experimental findings and exploring unexplored territories. The authors discuss the range of properties that can be calculated using DFT, including geometries, energies, reaction mechanisms, and spectroscopic properties such as infrared, optical, X-ray absorption, Mössbauer, and magnetic properties. They highlight the strengths and limitations of current methods, emphasizing the importance of hybrid functionals like B3LYP and TPSSh for achieving high accuracy in certain systems. The article also covers specific applications in DFT, such as the optimization of geometries, prediction of vibrational frequencies, and the analysis of optical spectra, X-ray absorption spectroscopy, Mössbauer spectroscopy, exchange couplings, and electron paramagnetic resonance (EPR) spectroscopy. Despite the overall reliability of DFT, the authors caution that errors can be significant and that validation is essential for enhancing the credibility of DFT studies. They also discuss the need for further developments in DFT, including improvements in functionals, treatment of electronic relaxation and excited states, and the inclusion of magnetic and relativistic effects.The article provides an overview of the application of density functional theory (DFT) in bioinorganic chemistry, particularly in the modeling of structures, properties, and processes related to photosynthesis. DFT has become a valuable tool for validating experimental findings and exploring unexplored territories. The authors discuss the range of properties that can be calculated using DFT, including geometries, energies, reaction mechanisms, and spectroscopic properties such as infrared, optical, X-ray absorption, Mössbauer, and magnetic properties. They highlight the strengths and limitations of current methods, emphasizing the importance of hybrid functionals like B3LYP and TPSSh for achieving high accuracy in certain systems. The article also covers specific applications in DFT, such as the optimization of geometries, prediction of vibrational frequencies, and the analysis of optical spectra, X-ray absorption spectroscopy, Mössbauer spectroscopy, exchange couplings, and electron paramagnetic resonance (EPR) spectroscopy. Despite the overall reliability of DFT, the authors caution that errors can be significant and that validation is essential for enhancing the credibility of DFT studies. They also discuss the need for further developments in DFT, including improvements in functionals, treatment of electronic relaxation and excited states, and the inclusion of magnetic and relativistic effects.