In comparison between the GCMC and NLDFT methods, the NLDFT method assumes that adsorptive molecules are approximated to spherical shape, while the GCMC method assumes that N2 and CO2 molecules are placed at the LJ2/LJ3 center, to calculate interaction between actual molecules (atoms) by handling quadrupole moments (electric charges) individually (Fig. 4). With the NLDFT method, a point that minimizes energy is calculated. However, the GCMC method may not always provide accurate equilibrium state depending on preset conditions. Therefore, try-and-error (changing simulation sizes) is required for this method.