Multiphase density functional theory parameterization of the Gupta potential for silver and gold

TL;DR

This paper develops a multiphase density functional theory-based parameterization of the Gupta potential for silver and gold, enabling accurate modeling of nanostructures across different phases and validating it through molecular dynamics simulations and nanocluster deposition studies.

Contribution

It introduces a new multiphase parameterization of the Gupta potential for Ag and Au based on DFT energies, improving transferability for nanostructure simulations.

Findings

The parameters accurately reproduce DFT energies across multiple phases.

The Ag cluster transforms from FCC to icosahedral structure at room temperature.

Optimal deposition temperature for Ag nanoclusters is around 500 K.

Abstract

The ground state energies of Ag and Au in the face-centered cubic (FCC), body-centered cubic (BCC), simple cubic (SC) and the hypothetical diamond-like phase, and dimer were calculated as a function of bond length using density functional theory (DFT). These energies were then used to parameterize the many-body Gupta potential for Ag and Au. This parameterization over several phases of Ag and Au was performed to guarantee transferability of the potentials and to make them appropriate for studies of related nanostructures. Depending on the structure, the energetics of the surface atoms play a crucial role in determining the details of the nanostructure. The accuracy of the parameters was tested by performing a 2 ns MD simulation of a cluster of 55 Ag atoms -- a well studied cluster of Ag, the most stable structure being the icosahedral one. Within this time scale, the initial FCC lattice was found to transform to the icosahedral structure at room temperature. The new set of parameters for Ag was then used in a temperature dependent atom-by-atom deposition of Ag nanoclusters of up to 1000 atoms. We find a deposition temperature of 500 $\pm$50 K where low energy clusters are generated, suggesting an optimal annealing temperature of 500 K for Ag cluster synthesis.