Theoretical study of the adsorption of 2H on Sin (n = 3, 5-10) clusters

The geometries and energies of SinH2 (n = 3, 5-10) have been systematically investigated by means of MP2/6-311++G∗∗//MP2/6-31G∗∗ and B3LYP/6-311++G∗∗ schemes. Several geometric arrangements have been considered for each cluster. All the geometries considered have been completely optimized within the given symmetry constrains. The results show that the ground state geometries of Si4H2, Si6H2, and Si8H2 are attaching two H-atoms to one Si-atom and others are bonding two H-atoms to two Si-atoms. The results of the lowest energy structure of SinH2 at MP2 levels are the same as those of results at B3LYP levels with the exception of Si5H2. However, the MP4(SDQ) result is the same as the B3LYP for Si5H2. At B3LYP level of theory, dissociation energies of the lowest energy structures of SinH2 (n = 3-10) have been computed and used to understand relative stability. Other properties, such as HOMO-LUMO gap, hardness, vertical electron affinities, and vertical ionization potential have been assessed.