  Evolutionary structure searches are used to predict a new class of compounds
in the lithium--rich region of the lithium/hydrogen phase diagram under
pressure. First principles computations show that LimH, 4<m<9, are stabilized
with respect to LiH and Li between 50-100 GPa. The building block of all of the
lithium subhydrides is an Li8H cluster, which can be thought of as a
superalkali. The geometries and electronic structures of these phases is
analogous to that of the well-known alkali metal suboxides.
