Calculation methods that are used in the molecular simulation can be grouped into quantum mechanics or classical simulation methods. The level of theory / computational method required depends on the property of interest. For properties that require electronic structure and information about the exact binding sites, quantum mechanical methods are used. However, due to the high computational cost of quantum mechanical methods, the size of the system to model needs to be carefully chosen. Quantum mechanics based on wave function theory can only be applied to small cluster models of MOFs capturing the region of interest and limited to a few tens of atoms. Consequently, small cluster models are unable to describe long range dispersion interactions, In addition, cutting the MOF to create a feasible cluster model requires capping the cut points with e.g. hydrogen atoms or methyl groups, which introduces electronic effects not present in the parent periodic structure. For full unit cell MOF structures, Quantum mechanics based on DFT can be used to simulate systems as big as 100-1000 atoms . While possible on handfuls of chosen MOFs, the expense of these quantum mechanical approaches means they cannot support screening large subsets of MOFs.