Hydrogen quantum effects in hydride LaNi(5)H(7).

Energy eigenvalues and wave functions of hydrogen atoms in hydride LaNi(5)H(7) are calculated. First-principles electronic structure calculations are employed to obtain the three-dimensional potential energy structure of each hydrogen site. These quantum effects are not negligibly small in evaluation of enthalpy of formation, an important property of hydrogen storage. Including the temperature effect from hydrogen gas, experimental values are well reproduced. The excitation probability of inelastic neutron scattering is also calculated using the wave functions obtained.