| Great attention was paid to design and synthesize new MOFs for hydrogen storage. Using molecular simulation method to predict the capabilities of hydrogen storage of different materials under various conditions can provide theoretical guidance to experimental research and to reduce the time and money costs. Underlying force field is the center issue of molecular simulation, but existing parameters for hydrogen adsorption in MOFs were derived by fitting limited experimental data or taken from generic force fields, both are limited in accuracy and reliability.In this work, we started from quantum chemistry calculations on model compounds of MOF-5 to study the interactions between H2 and MOF-5. The model compounds were organic linker and metal oxide cluster. The calculations were performed at the MP2 level of method. Based on the quantum chemistry data, we derived classical force field parameters which included charge and van der Waals parameters. The Feynman-Hibbs effective potential was used to consider the quantum effect at low temperature. Conventional grand canonical Monte Carlo (GCMC) simulations were carried out to predict the hydrogen adsorption isotherms of MOF-5 with the newly developed force field. The simulation results agree well with experiment results in a broad range of temperatures and pressures, which demonstrated the reliability of the force field and simulation method.Since the force field parameters were based on quantum chemistry calculations independently from any experimental data, this approach can be used to predict the relative capabilities of hydrogen storage for various MOFs reliably. In this work, we reported the predicted hydrogen adsorption/release capabilities between 0.1 and 8 MPa at various temperatures for a series of MOFs materials. The relationship between the structure and storage capacity was analyzed. We found that the fraction of free volume is the key factor that influences the hydrogen storage capability for given chemical constitutions.
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