Dissociation dynamics of D2 on rigid and nonrigid Ni clusters

Abstract

We present results of a theoretical study of the dissociation dynamics of D2 on NiN clusters with N=3–13. First, the semiempirical density functional based molecular dynamics/Monte Carlo corrected effective medium method was used to predict the interaction energies of various Ni clusters in this size range. We identified the most stable clusters and found that only N=9 possesses two nearly equally stable isomers with an energy difference of only 0.03 eV. Second, we performed classical trajectory simulations of the reactions in which the Ni atoms were allowed to move. The dissociation cross sections from calculations on the nonrigid clusters were nearly equal to those obtained with the rigid Ni cluster. A particularly intriguing result was that the dissociation cross sections calculated for the two isomers of Ni9 differed significantly, especially at low collision energy. Third, we showed that the dissociation probabilities as functions of the impact parameter and relative translational energy were fit with good accuracy as a simple function of a single variable E⊥, the component of translational energy perpendicular to the surface of the cluster. This indicated that the normal energy scaling of the dissociative sticking probability observed in some gas/surface systems may have an equivalent behavior in gas/cluster systems.