Di-hydrogen Storage in Novel (C<sub>n</sub>Ge<sub>n</sub>)<sub>2</sub> Nanostructures: Theoretical Study at Density Functional Theory (DFT) Level

The Di-hydrogen solid-state is formed only at very low temperatures and pressures exceeding 1.5 million atmospheres. These draconian conditions are harmful to the economic and safe use of hydrogen, even if several studies refer to solid hydrogen which in reality is hydrogen adsorbed or absorbed on metallic surfaces or other. The objective of this research is to find new nanostructures with cages form that are able to confine a larger number of hydrogen molecules, potentially suggesting the geometry of the unit cell of solid hydrogen under standard conditions of (P, T). For this purpose, we use the density functional theory (DFT) method with the B3LYP and ωB97XD functional with the 6-31+G* basis. The MP2/6-311G++(d,p) level leads to the same results. The calculations of energies formation, infrared (IR) spectra, the shape of the molecular orbitals frontiers (MOF) and the Energy Gap will be done at theoretical level. These cage nanostructures are potential candidates for the Di-hydrogen storage. The 2H2 complex adopts a planar geometry, whereas 3H2 assumes a bi-pyramidal geometry with a square base.