Hybrid quantum mechanics/molecular mechanics (QM/MM) simulations have become a popular tool for investigating chemical reactions in condensed phases. In QM/MM methods, the region of the system in which the chemical process takes place is treated at an appropriate level of quantum chemistry theory, while the remainder is described by a molecular mechanics force field. Within this approach, chemical reactivity can be studied in large systems, such as enzymes. Using quality management (QM) to calculate the properties of a large chemical library is time-consuming and costly. High-precision QM/MM calculation is a multi-scale calculation method to study ligand binding.