A computer simulation study of the interaction between passivated and bare gold nanoclusters

Abstract

Molecular dynamics simulations have been performed with the objective of understanding the phenomenon of nanoparticle aggregation. We have attempted to calculate the free energy associated with the interaction between two 38-atom gold nanocores, with attached passivating thiol chains, in a supercritical ethane solvent and in the vacuum, and without passivating chains in ethane at the critical density and twice the critical density. Our model differs from those used by others in that each gold nanocore is bound by a realistic metal potential that is not formally rigid. In the case of the passivated nanoparticles, we observe profound structural changes in the nanocores, which radically affect the nature of the interaction between them-to the extent that fusion of the two gold nanocores cannot be prevented under the conditions examined. Bare nanocores, on the other hand, do not exhibit much structural change until close contact occurs. The fused nanocores in the passivated and bare nanocore systems have significantly different morphologies. There is evidence that at higher solvent density, the interaction between bare nanocores is slightly repulsive.

A Unified AMBER-Compatible Molecular Mechanics Force Field for Thiolate-Protected Gold Nanoclusters

“…Whereas density functional theory (DFT) has been widely used to investigate the electronic, optical, and even catalytic properties of gold nanoclusters, the system size and time scales that must be reached to investigate the interactions between gold clusters and biomolecules precludes DFT and necessitates classical molecular dynamics simulation in combination with a molecular mechanics force field instead. To date, several molecular dynamics simulations have been performed on systems containing gold, either as a surface , or nanoparticle. − However, as most of these studies were focused on a specific gold cluster, the force field parameters are often not transferable to clusters with different sizes or ligands.…”

Functional-Group Effect of Ligand Molecules on the Aggregation of Gold Nanoparticles: A Molecular Dynamics Simulation Study

“…Therefore, determining the factors affecting the aggregation/dispersion behaviors of gold NPs and controlling these behaviors are crucial. Many experimental − and molecular dynamics (MD) simulation studies − have been performed to understand the aggregation/dispersion behaviors of functionalized gold NPs. In these simulation studies, the coarse-grained (CG) model − and realistic atomistic model − are widely used.…”

“…Many experimental − and molecular dynamics (MD) simulation studies − have been performed to understand the aggregation/dispersion behaviors of functionalized gold NPs. In these simulation studies, the coarse-grained (CG) model − and realistic atomistic model − are widely used. There are a few simulation studies that have examined the effect of the polarity of the terminal groups of ligand molecules on the aggregation of functionalized gold NPs. ,, …”

High-performance computing in the chemistry and physics of materials

“…Walsh (2011) explores the effects of dimensionality on the widely studied hybrid organic-inorganic materials; while both Lal et al (2011) and Tran & Johnston (2011) model metal nano-clusters, with the former addressing the differences between bare gold clusters and those which have been passivated by sorbed thiols (figure 2); and the latter the structures and properties of gold-platinum alloy clusters. The growing field of oxide nano-cluster science is addressed by Woodley (2011) who reports an extensive series of predictions of the structures and electronic properties of sesquioxide nano-clusters.…”