Functionalized boranes for hydrogen storage.

Using density functional theory, the generalized gradient approximation for the exchange-correlation potential and Møller-Plesset perturbation theory we study the hydrogen uptake of Li- and Mg-doped boranes. Specifically, we calculate the structures and binding energies of hydrogen molecules sequentially attached to LiB(6)H(7), LiB(12)H(13), Li(2)B(6)H(6), Li(2)B(12)H(12), MgB(6)H(6), and MgB(12)H(12). Up to three H(2) molecules can be bound quasi-molecularly to each of the metal cations with binding energies per H(2) molecule ranging between 0.07 eV and 0.27 eV. The corresponding gravimetric densities lie in the range of 3.49 to 12 wt %, not counting the H atoms bound chemically to the B atoms.