The pore size of a metal-organic framework MOF plays a significant role in its ability to absorb carbon dioxide molecules. MOFs are porous materials composed of metal ions or clusters connected by organic linkers, forming a three-dimensional network with well-defined pores. The pore size, along with other factors such as pore shape, surface area, and chemical functionality, can influence the adsorption capacity of MOFs for CO2.To study the effect of pore size on CO2 adsorption, we can use computational methods to compare the adsorption capacity of three different MOFs with varying pore sizes. Here, we will use grand canonical Monte Carlo GCMC simulations, which are widely employed to study gas adsorption in porous materials.1. Selection of MOFs: Choose three MOFs with different pore sizes. For example, MOF-1 with small pores, MOF-2 with medium pores, and MOF-3 with large pores. Ensure that the MOFs are well-characterized and have known crystal structures.2. Computational setup: Obtain the crystal structures of the selected MOFs from a database such as the Cambridge Structural Database CSD or the Crystallography Open Database COD . Prepare the structures for GCMC simulations by removing any solvent molecules and optimizing the geometry using density functional theory DFT or another suitable method.3. GCMC simulations: Perform GCMC simulations for each MOF at various pressures and temperatures relevant to CO2 capture applications e.g., 1 bar and 298 K . Use an appropriate force field to describe the interactions between the CO2 molecules and the MOF framework. Calculate the adsorption isotherms, which show the amount of CO2 adsorbed as a function of pressure.4. Analysis: Compare the adsorption isotherms of the three MOFs to determine the effect of pore size on CO2 adsorption capacity. Calculate the CO2 uptake at specific pressures e.g., 1 bar and the isosteric heat of adsorption, which provides information about the strength of the interactions between CO2 and the MOF.Based on the results of the GCMC simulations, we can draw conclusions about the relationship between pore size and CO2 adsorption capacity in MOFs. Generally, MOFs with larger pore sizes and higher surface areas tend to exhibit higher CO2 uptake due to the increased availability of adsorption sites. However, other factors, such as the strength of the interactions between CO2 and the MOF, can also play a role in determining the overall adsorption capacity. By comparing the adsorption properties of MOFs with varying pore sizes, we can gain insights into the design principles for the development of new MOFs with enhanced CO2 capture performance.