Hydrogen has large influence on physical and chemical properties of Earth's constituent minerals such as melting temperature and rheological properties. In order to determine the solubility of water in mantle minerals and estimate how much water is stored in Earth's interior, it is critical to investigate the forms of hydrogen in these minerals under high pressure at the atomistic level. We have investigated structural and vibrational properties of hypothetical fully hydrated wadsleyite (Mg7Si4O14(OH)2) using first principles techniques. Cell parameters and linear compressibilities are good agreement with experiments except a axis. We obtained bulk modulus about 138 GPa (K' = 4.5). Using first principles perturbation theory, we have calculated vibrational properties of hydrous wadsleyite. The O-H stretching vibrational frequencies are 3474, 3483, 3503 and 3505 cm-1.
