Molecular dynamics simulations of palladium cluster growth on flat and rough graphite surfaces

¹ Groupe de Recherches sur l'Énergétique des Milieux Ionisés, UMR6606 CNRS-Université d'Orléans, BP 6744, 45067 Orléans, Cedex 2, France
² Centre de Ressources Informatiques de Haute-Normandie, 745 avenue de l'Université, 76800 Saint Étienne du Rouvray, France

Corresponding authors: pascal.brault@univ-orleans.fr guy.moebs@crihan.fr

Received: 17 December 2003
Revised: 18 March 2004
Accepted: 30 March 2004
Published online: 25 June 2004

Abstract

Parallel Molecular Dynamics simulations are conducted for describing growth on surfaces with different kind of roughness: a perfect ordered crystalline flat graphite surface, a disordered rough graphite surface and flat surface with an ordered localized defect. It is shown that disordered rough surfaces results in a first step to reduction of the sticking coefficient, increased cluster density, size reduction. Structure of the clusters shows the disappearance of the octahedral site characteristic of compact structure. Isolated defect induces cluster-cluster interactions that modify growth compared to perfect flat surface. Kinetic study of growth shows power law t^αz evolution for low impinging atom kinetic energy. Increasing kinetic energy, on all kinds of surfaces, results in a slightly larger exponent z, but fitting by an exponential function is quite good too. Lattice expansion is favoured on rough surfaces but increasing incoming atom kinetic energy weakens this effect.