Abstract: Using density functional theory associated with B3LYP method with 6-31G** and Lanl2dz basis sets, the optimization of the geometries and the calculation of frequencies for (MN)nHm (M=Ga, In; n= 1-4; m=1, 2) clusters were carried out, respectively. In addition, the most stable structures, binding energy of hydrogen atom, and energy gap were obtained. The results showed that the ground state structures of (MN)nH (M=Ga, In; n=1-4) and (MN)nH2(M=Ga, In; n=1-4) clusters were doublet and singlet states, respectively. When the number of hydrogen atom was one, the isomer in which hydrogen atomwas added in nitrogen atomwas more stable than that in M(M=Ga, In) atom. If there was a N3 unit, the isomers in which hydrogen atom was added in nitrogen atom of either side in N3 unit were the same and the most stable. While the number of hydrogen atom was two, except for n is equal to one, the isomer in which two hydrogen atoms were added in nitrogen atoms, respectively, was the most stable. If there was a N3 unit, the isomer in which two hydrogen atoms were added in the two farthest nitrogen atoms in N3 unit, respectively, was the most stable. Larger binding energies of a single hydrogen atom on small MN clusters and larger highest occupied and lowest unoccupied molecular-orbital energy gaps for GaNH, (GaN)3H, and InNH make these species have more stable.

Key words: Density functional theory, Hydrogenated galliumnitride cluster, Hydrogenated indiumnitride cluster, Structure and stability