H-2 dissociation on the Group 13 metal cluster Al-13 to form Al13H2 dihydride is investigated using density functional theory (DFT). The reaction pathway has been described and DFT method dependence of the calculated energetics is studied. To this end, 10 carefully chosen density functionals of the Generalized Gradient Approximation (GGA), hybrid GGA, meta-GGA and hybrid meta-GGA type are used in conjunction with the correlation-consistent basis sets (aug-cc-pVxZ where x = D and T). (C) 2009 Elsevier B. V. All rights reserved.