The Theoretical Biochemistry Group (GBQT) researches at the microscopic level photochemical, photophysical, physical, or chemical processes in small molecules and proteins using computational simulations. The methods depend on the type of problem and the size of the system. To study processes in small molecules, a wide range of quantum mechanical (QM) methods are applied: semiempirical methods, density functional theory, post-Hartree-Fock methods such as MP2, and Coupled Cluster. To study processes in large molecules, such as proteins, Molecular Mechanics (MM) and Quantum Mechanics (QM) methods are used. Chemotypological and QSAR methods are also implemented.