Blocking spheres were calculated using Zeo++ to block the inaccessible regions of the MOF structures . The framework atoms of the MOF structures were described by UFF . CO 2 and H 2 O molecules were described by the TraPPE forcefield and TIP4P/2005 forcefield respectively . The gas-framework interactions were modeled using Lennard Jones potential, truncated at 12 Å, with tail corrections . The Lennard Jones interactions between dissimilar atoms were approximated using Lorentz-Berthelot rules . The Coulombic electrostatic interactions were computed using Ewald summation.