Structure and energetics of LiBH4 and its surfaces:: A first-principles study

The structure and energetics of LiBH4 and its surfaces have been studied using the density functional theory (DFT) plane-wave method. The DFT relaxed bulk LiBH4 structure is in agreement with the synchrotron X-ray diffraction results. Four low-index surfaces, (100), (010), (001), and (101), have been created from the relaxed bulk structure. The (010), (100), and (101) surfaces were found to have a similar surface energy, similar to0.12 J/m(2), and are significantly more stable than the (001) surface. The H vacancy formation energies on the low-energy surfaces have been found in a narrow range of 180-200 kJ/mol. The formation energy for the first H vacancy on the (001) surface is 165.8 kJ/moI and is the lowest among all the surfaces.