Hydrogen storage in metal-organic frameworks

Understanding of the physisoultion of H-2 in metal-organic frameworks (MOFs) is critical to improving its performance for hydrogen storage. By using first-principles calculations employing the van der Waals density functional (vdW-DF) method which can properly describe the vdW interaction, we investigate the binding energy of H-2 in MOF-5 crystal. The accuracy of this methodology is first examined and good accuracy comparable to the correlated wavefunction methods is found. Calculation's for the true crystal structure show that the small fragment models used in previous calculations cannot represent well the property of the crystal. The good accuracy and the ability to deal with the true crystal structure make the vdW-DF method a good candidate for investigating hydrogen storage in MOFs.