DFT for periodic systems. DFT has become the working horse for the calculations of structures and properties of MOFs and COFs. Unfortunately, there is no DFT software available that simultaneously offers all necessary features for this materials class. Periodic systems are typically efficiently treated using plane wave basis sets in conjunction with the projected augmented wave (PAW) method. They are readily available in commercial (VASP, CASTEP ) and free (QuantumEspresso ) software. Large pores and the possibility to directly compare to molecular systems makes also local basis function approaches interesting, with typical representatives being AMS/BAND, CRYSTAL, cp2k, and FHI/aims. They also offer access to computationally affordable hybrid functionals PBE0 and HSE06. London dispersion interactions need to be accounted for, most popular is the D3 approach by Grimme or the MBD approach. Local basis functions should have triplezeta quality with polarization functions to allow for the correct description of the decay of the electron density into the pore centers.