Origin and Basic Concepts

In the second part of this chapter, I will explain how we, computational chemists, apply quantum mechanics to the study of chemical reactions, which are the approximations that we do, and how do we obtain valuable information by means of applying these approximations. 

Finally, in the last part of this chapter, I will briefly describe the methods that I have used during this thesis. This last part is probably the part that involves more mathematical equations, but don t worry about it because I will only include the most important ones. Furthermore, my intention in this last part of the chapter is not to do an exhaustive description of the methods, but to provide a comprehensive view of the original concepts, approximations and ideas that are behind them. 

Melchor, A Theoretical Study of Pd-Catalyzed C-C Cross-Coupling Reactions, Springer Theses, DOI 10.1007/978-3-319-01490-6 2, 

With a role similar to Newton s second law in classical mechanics, the SchrOdinger equation in quantum mechanics describes how the wavefunction evolves in time  

In this last equation, H is the Hamiltonian, an operator that generates the time evolution of quantum states and provides the value for the total energy of the system. By analogy with classical mechanics, this operator is generally expressed as the sum of the operators for the kinetic (T) and potential (V) energies  

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