  We present a first-principles study of geometrical structure and energetics
of hydrogen adsorbed on hexagonal single-walled silicon nanotubes (SiNTs). The
adsorption behaviors of hydrogen molecules in SiNTs are investigated. The
binding energies for the most stable physisorbed configurations are calculated
to be less than 0.1 eV. The energy barriers are also investigated for
dissociation of H2 molecules. Finally, we consider encapsulation of H2
molecules in SiNTs. The possibility of SiNTs as hydrogen storage materials is
discussed.
