The aim of this thesis is investigation of the adsorption process in the oxygen storage container in molecular level. By inserting porous media in the oxygen storage container, it is expected oxygen content increases in constant volume and pressure. To consider that, some porous media such as zeolites, IRMOFs, and CNTs are selected. Then they have imposed to the oxygen gas and amount of gas adsorption is calculated using GCMC simulation. CNT1111 shows the most oxygen adsorbtion among all other candidates. In the next step, cation is physically doped in the CNT structure and GCMC siulation is repeated to investi- gate the effect of cation in amount of adsorption. The obtained isotherms show that cation inclusion in the carbonic structure improves the amount of gas adsorption. Lenard-Jones force field was responsible for the interaction between monomers in all previous simulation. However, the correctness of this force field for the new system in which cation is included is questionable. To find the effective force filed for thses kind of systems, the potential energy curve for the interaction between different cations such as Na+ ,Li+ , K+, and Cs+ and some gases (O2 , N2 , H2 , H2O, H2S, and CO) are obtained using quantum mechanics techniqes. The obtained curves are fitted on the known potential such as LJ12-6, LJ9-6, Morse, and Buchingham. Non of the mentioned potential could not describe the interaction between desired systems approprately. In this thesis, Morse potential is improved and an extended-Morse force field is introduced to describe the interaction between monomers in these kind of systems appropriately. The results of this part provide a valuable data base for researchers who are interested to study the gas adsorption in cation-doped carbonic structure by molecular simulation approaches. The effect of size and curvature of carbonic structure on the force field generation have been studied by DF-SAPT(DFT) method. Calculations have been done for Li+-doped carbonic structure with different size and curvature and some gases (O2, N2 ,H2 ,H2O , H2S, CO2, and CO). The results show that the carbonic system size and its curvature does not effect on the interaction between cation-doped carbonic structure and gases. It is important so that one could choose a basic part of carbonic structure (a benzene ring) as a model and provide a general force field for these kind of systems.
