We present results of a six-dimensional quantum dynamics study of H-2 (nu = 0, J = 0) scattering from Pd(1 1 1) using a potential energy surface obtained from density functional theory calculations. Quantum dissociative adsorption probabilities agree with experimental data and provide new evidence on the importance of dynamic trapping (induced by translation to rotation energy exchange) at low energies. We analyse the role of the vibrational zero point energy in classical calculations and the suitability of the so-called classical and quasi-classical approaches to describe dissociative adsorption dynamics for a non-activated system. (C) 2002 Published by Elsevier Science B.V.