for For the case where Coulombic interactions are included for CO 2 , the following method is used: at a position r, we search for the orientation of the adsorbate molecule that would give the most favorable interactions. For this purpose, we noticed that the Coulombic interactions between an adsorbate molecule and an atom of the MOF are, in general, larger in magnitude than the Lennard-Jones interactions, except when one atom of the adsorbate molecule is too close to the atom of the MOF. From this observation, we concluded that the Lennard-Jones interactions forbid some orientations while the Coulombic interactions push to a favorable orientation. Therefore, we compute two directions: an approximate optimal direction for Lennard-Jones interactions which are away from the 'most forbidden directions' and an approximate optimal direction for Coulombic interactions. We then compute the sum of Lennard-Jones and Coulombic interactions in 10 directions between the two computed optimal directions and retain the minimum energy for these 10 calculations.