From the successful optimizations, 74.51% of all cell parameters are within 5% of the reference value, 87.40% are within 10% and 95.13% are within 20% as shown in Figure . As the lattice optimizations allowed complete relaxation of cell vectors and angles, one source of large errors in lattice parameters is breathing MOFs. Breathing in MOFs is a behaviour of reversible flexible framework occurs upon guest adsorption, temperature, pressure or other stimuli, which allows a large change in the unit cell. For example, Refcode FERWAC_clean 49 begins with a=9.97 Å, b=15.74 Å, c=15.74 Å, but optimized to a narrow pore structure with a=7.80Å b=15.31Å, c=15.31Å. Similar effects are observed in e.g. refcode GUSNEN01_SL , QOVWOO_SL , QUQGAL_clean 52 , QOSJIT_clean , FOFCOU_clean 54 , QOSJOZ_clean 53 , QOVWOO01_clean , CEFDAU_clean 56 and SABWAU_SL . Breathing MOFs are responsible in some structures with both +20 to +30 and -20 to -40 deviations in lattice parameters (e.g. the a parameter of FERWAC_clean 49 changes from 9.97Å to 7.80Å after optimization). From the successful optimizations, 74.51% of all cell parameters are within 5% of the reference value, 87.40% are within 10% and 95.13% are within 20%. As the lattice optimizations allowed complete relaxation of cell vectors and angles, one source of large errors in lattice parameters is breathing MOFs. Breathing in MOFs is a behaviour of reversible flexible framework occurs upon guest adsorption, temperature, pressure or other stimuli, which allows a large change in the unit cell. For example, Refcode FERWAC_clean 50 begins with a=9.97 Å, b=15.74 Å, c=15.74 Å, but optimized to a narrow pore structure with a=7.80Å b=15.31Å, c=15.31Å. Similar effects are observed in e.g. refcode GUSNEN01_SL , QOVWOO_SL , QUQGAL_clean 53 , QOSJIT_clean 54 , FOFCOU_clean 55 , QOSJOZ_clean 54 , QOVWOO01_clean , CEFDAU_clean 57 and SABWAU_SL . Breathing MOFs are responsible in some structures with both +20 to +30 and -20 to -40 deviations in lattice parameters (e.g. the a parameter of FERWAC_clean 50 changes from 9.97Å to 7.80Å after optimization).