Molecular Dynamics Simulation of Hydrogen Absorbing Palladium : Turnover of Hydrogen Absorption Heat into Palladium

概要

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Molecular dynamics simulations were carried out for hydrogen absorption by palladium in various atomic ratios to identify the reason why hydrogen absorption heat changes from exothermic to endothermic at a high atomic ratio.Classical two-body interactions were used as interatomic potentials for these simulations in order to simplify the calculation.Pd-Pd and Pd-H interatomic potentials were determined empirically by fitting the calculated physical properties of PdH_x's with observed values at an atomic ratio, and the H-H potential was given by a screened Coulomb potential.Calculated molar volumes and absorption enthalpies were consistent with observed data for a wide range of atomic ratios.These results show that the simple approach was sufficient to evaluate the absorption heat of PdH_x.Analyses of crystal structure and the averaged H-H coordination number indicate that the change of the absorption heat from exothermic endothermic was not caused by a structure change, but by H-H repulsion.
社団法人応用物理学会の論文
2000-04-15