To address the anharmonicity of the vibrations of adsorbed H2, calculations for anharmonic corrections were performed. When H2 is bound at an M I site, it is reasonable to assume that the intramolecular vibration of H2 (H-H stretching mode) is completely decoupled from the vibrational modes of the MOF cluster. With that assumption, determining the anharmonic correction to H2 vibration essentially reduces to solving a one-dimensional Schrödinger equation of the form: