ARI (1998) 51 : 20 — 23 Springer-Verlag 1998 ORIGINAL ARTICLE S. O zyelik · P. Durmus , · Z. B. Gu ¨ veny Molecule-cluster collisions: reaction of D 2 with Ni 14 Received: 20 September 1997 / Accepted: 15 January 1998 Abstract The reactive channel (dissociative of the molecu- le on the cluster) of the D # Ni collision system is studied via quasi-classical molecular dynamics (MD) computer simulations. This is analysed as functions of the initial rovibrational molecular state and collision energy. The Ni cluster is at room temperature. The geometry of the cluster is obtained by embedded-atom (EA) model potential, and the interaction between D and Ni is modelled by LEPS (Landon-Eyring-Polanyi-Sato) poten- tial surface. Key words Molecular dynamics ) Nickel cluster ) Collisions ) Dissociative chemisorption ) Deuterium molecule 1 Introduction Clusters play a special role as a new state of matter. This state fills the gap between gases, on the one hand, and liquids and solids on the other, and plays a central role in a variety of natural phenomena and processes of envir- onmental concern, etc. Heterogeneous catalysis is one of the process the control over which may be greatly enhanced through the understanding of the mechanisms of cluster-molecule, especially metal cluster-molecule, in- teractions. Therefore, the processes induced by collisions of metal clusters with molecules have been and remain one S.Ozielik ( ) ) P. Durmus , Department of Physics, Faculty of Arts and Sciences, Gazi University, TR-06500 Ankara, Turkey Tel: #90 312 2123930; fax: #90 312 2122279; e-mail: ozcelik@ quark.fef.gazi.edu.tr Z. B. Gu¨veni Department of Computer Engineering, hankoya University, TR-06530 Balgat Ankara, Turkey Presented at the International Symposium on Lasers, Atomic and Molecular Physics, Istanbul Technical University, Maika Campus, Istanbul, Turkey, 16 —20 September 1997 of the central subjects of the experimental cluster research (Elkind et al. 1988; Irion and Schnabel 1991). The majority of the related theoretical studies are electronic structure calculations performed at fixed nuclear geometries (Upton 1986). Cluster-molecule systems have been treated dyna- mically in some number of theoretical studies (Raghavan et al. 1989; Adams 1990; Jellinek and Gu¨veni, 1991a; Jellinek et al. 1992; Gu¨veni et al. 1992). In what follows we present results of a simulation study of collisions of a D molecule with an Ni cluster. In Sect. 2, the interaction potential and the computational details are outlined. The focus is on the reactive channel of the interaction, and the effect of the initial rovibrational state of the molecule on the reactivity is discussed in Sect. 3. 2 The potential and computational details The potential energy surface (PES) » defining the forces acting on each atom in D # Ni collision system is of the form »"» #» where » is a so-called embedded-atom potential des- cribing the interaction between the Ni atoms, and » is a function representing the D!D and D —Ni interac- tions. We have employed » which, in addition to the bulk properties of nickel, also correctly reproduces the equilibrium bond length (2.2 A s ) and bond energy ( + 1.95 eV) of Ni (for more details see Gu¨ veni et al. 1992). The so-parameterized EA potential can be expected to be of relevance for the intermediate size range, i.e. clusters, as well. The LEPS function is the PESII of Raghavan, Stave, and De Pristo (RSD) (Raghavan et al. 1989), modified by a smoothing function used by Truong et al. (1989) (details will be given elsewhere). We have chosen PESII, rather than PESI employed by RSD, because the former was fitted to reproduce the binding energy and the binding height of an H atom on the threefold site of an icosahedral