  We have performed cascade genetic algorithm and ab initio atomistic
thermodynamics under the framework of first-principles density functional
theory to study the (meta-)stability of a wide range of LixNy clusters. We
found that hybrid xc-functional is essential to address this problem as a
local/semi-local functional simply fails even to predict a qualitative
prediction. Most importantly, we find that though in bulk Lithium Nitride, Li
rich phase, i.e. Li3N, is the stable stoichiometry, in small LixNy clusters
N-rich phases are more stable at thermodynamic equilibrium. We further show a
that these N-rich clusters are promising hydrogen storage material because of
their easy adsorption and desorption ability at respectively low (< 300K) and
moderately high temperature (> 600K).
