High Temperature Molecular Dynamics Studies of Cluster Growth and Polymer Degradation

Abstract

Computer simulations have added a new scope to scientific research in the rapidly growing field of cluster physics and chemistry. In the last few years, numerous novel innovations in experimental cluster measurements and technologies led to the discovery of a richness of cluster geometries built up in many cases by cluster units with magic number of atoms.^1,2 Clusters in the liquid state have also been postulated.³ Heterogeneous catalysis, nucleation, physisorption, fragmentation either thermal or caused by energy or charge instabilities are some of the phenomena that need theoretical support- As is common in scientific investigation, the validity of a comparison between theoretical predictions and experiments may be sometimes questioned because of the complexity of the experimental interpretation as compared to the simplicity of the theoretical model. Furthermore, the testing of a theoretical prediction may be restricted because of limitations in the experimental state-of-the-art. Computer experiments have alleviated these bottlenecks in various areas of physical chemistry,⁴ and, hopefully this presentation will provide the reader extra insight in two selected high temperature processes that take place in flames. Two computer simulations studies will be considered. The first example is framed in Section 2, and concerns the study of the growth of silicon particles in a flame, with special emphasis on the irreversible energy accommodation that occurs in cluster-cluster collisions. The second example given in Section 3 describes the thermal degradation of simple polymers by depolymerization reactions that occurs, presumably, during the combustion of the material.