Hydrogen as an alternative fuel: An ab-initio study of Lithium Hydride and Magnesium Hydride

Citation:
Hydrogen as an alternative fuel: An ab-initio study of Lithium Hydride and Magnesium Hydride. United Kenya Club; 2013.

Abstract:

Limited energy resources and growing pollution associated with conventional energy production have stimulated the search for cleaner, cheaper and more efficient energy technologies. Hydrogen as a fuel is seen as one of the promising energy technologies alternative to fossil fuel. Metal hydrides have been suggested as potential candidates for the bulk storage of hydrogen. In this study, ab-initio calculations of metal hydrides that are promising candidates for hydrogen storage applications, that is, magnesium hydride (MgH2) and lithium hydride (LiH) was carried out using the Quantum Espresso computer code. The calculated quantities were the equilibrium structural parameters namely, the electronic properties as well as the thermodynamic properties. The calculated lattice parameters for MgH2 were a = 4.54 Å and c = 3.019 Å. Both values of a and c are in good agreement with experimental values of a = 4.501 Å and c = 3.01 Å. The calculated lattice parameter for LiH was a = b = c = 3.93 Å. The lattice parameter of LiH shows a correlation of approximately -3.79% with the experimental value of 4.083 Å. Thermodynamic properties of LiH were investigated by performing density functional theory within the quasi harmonic approximation. The temperature dependence of the heat capacity at constant volume CV, the Helmholtz free energy ∆F, the internal energy ∆E and the entropy ∆S was obtained. The thermodynamic properties and formation enthalpies are in good agreement with the experimental data.

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