The addition of a catalyst affects the energy barrier of a reaction mechanism and ultimately the rate of reaction by providing an alternative reaction pathway with a lower activation energy. Density functional theory DFT calculations can be used to predict these effects by modeling the interactions between the catalyst, reactants, and transition states involved in the reaction.In a chemical reaction, the energy barrier, or activation energy, is the minimum energy required for the reactants to transform into products. The higher the energy barrier, the slower the reaction rate, as fewer molecules possess the necessary energy to overcome the barrier. Catalysts work by lowering the activation energy, allowing more molecules to participate in the reaction and thus increasing the reaction rate.Density functional theory is a computational method used to study the electronic structure of molecules and materials. It is based on the idea that the energy of a system can be determined by the electron density distribution. DFT calculations can be used to model the interactions between the catalyst and the reactants, as well as the transition states that occur during the reaction.By performing DFT calculations on a reaction mechanism with and without a catalyst, chemists can compare the activation energies of the two pathways. If the catalyst provides a lower activation energy, it will increase the rate of reaction. Additionally, DFT calculations can help identify the specific interactions between the catalyst and reactants that contribute to the lowering of the energy barrier, providing insights into the design of more efficient catalysts for specific reactions.