Density-functional calculations of alkali and alkaline-earth alanates

4 Density-functional calculations of alkali and alkaline-earth alanates 

Density functional theory (DFT) has become a standard theoretical approach in the exploration of new solid-state hydrogen storage materials. Intense computational work has been attributed to the understanding of the promising alkali and alkali-earth alanate systems. Numerous theoretical studies, in particular, have focused on the systems of tetrahydridoalumate 

The other is a brute-force low-energy structure search 

Electronic stmcture studies identified many similarities in the chemical binding among different alkali and alkaline-earth aluminum hydrides, however, with no clear signs in explaining significant differences in the decomposition 

A more negative formation enthalpy is indicative of a more stable phase, relative to other candidate structures. Likewise, a more negative reaction enthalpy represents an increased favorability for the release of H2. There is one important difference that Li3AlH6 has a much more negative formation enthalpy than the heavier hexahydrides. It is too stable, which may make the reverse reaction thermodynamically unfavorable in the Li alanates. The lower 

---