Based on the alkali metal sodium atoms decorated tetrahedron

Si

4

small cluster

the geometric structures

electronic properties and hydrogen storage properties of tetrahedral

Na

4

Si

4

cluster were studied by using the Minnesota density functional theory (DFT

M06) method. The results show that the tetrahedron

Si

4

can be decorated by alkali metal Na atoms on the four surfaces stably and Na atoms do not occur clustering. Hydrogen molecules can be adsorbed around the Na atoms

in which every Na atom can adsorb six hydrogen molecules efficiently，corresponding to a maximum mass fraction of 19.15% with an average adsorption energies of

3.926～9.927 kJ·mol

-1

per H

2

molecule．The results demonstrate that the tetrahedral

Na

4

Si

4

cluster has the potential to become an effective hydrogen storage medium under the room temperature and atmospheric pressure conditions.