A quick method for developing interparticle force models of spherical gold nanoparticles from molecular dynamics simulation

Understanding and quantification of the interactions between gold nanoparticles (AuNPs) allows us to explore their potentials for a wide range of applications. In present work, the interactions between AuNPs of size ranging from 3 nm to 20 nm are investigated by molecular dynamics (MD) simulation and their interparticle force models are developed from a quick and effective approach. Specifically, an external force is initially applied to a pair of spherical AuNPs at certain surface separation to accelerate their approaching toward each other. Such applied force is then removed at a certain distance, which can avoid the potential impact of such external force on the calculated interaction forces between AuNPs. Our results show that the attractive force dominates the interactions between spherical AuNPs. Such force increases exponentially with the decrease of particle surface separation prior to particle collision, which can be described quantitatively by simple mathematical force models. In addition, simulation on two AuNPs with different sizes shows that the smaller particle tends to merge onto the surface of larger one upon their collision. The reported approach provides a quick way to developing the interparticle force models between nanoparticles of different materials and shape, which is of importance in exploring nanoparticle systems and their self-assembly