Molecular dynamics simulation of Pt on a vitreous silica surface

Abstract

The molecular dynamics (MD) computer simulation technique was used to simulate the deposition and cluster growth processes of Pt on a vitreous silica surface. Using a combination of a modified Born-Mayer-Huggins potential (for the substrate) and a Lennard-Jones potential (for the adatoms), the structural features of clusters resulting from four different deposition processes were analyzed and compared to EXAFS results of a similar system. Two of the four deposition processes allowed cluster growth with little interaction with the substrate (by physical separation) and showed comparable results to the EXAFS data. In the two remaining deposition processes, cluster formation occuring with increasing interaction with the substrate resulted in smaller, less three-dimensional particles. This result is in accordance with experimental and theoretical calculations suggesting limited mobility of metal atoms to diffuse once in contract with the amorphous surface.