Abstract
For the kinetic simulation of metal nanoparticles, we developed a self-consistent coordination-averaged energies for Au atoms based on energy properties of gold bulk phases. The energy barrier of the atom pairing change is proposed and holds for the microscopic reversibility principle. By applying the lattice kinetic Monte Carlo simulation on gold films, we found that the atomic diffusion of Au on the Au(111) surface undergoes a late transition state with an energy barrier of about 0.2 eV and a prefactor between 40~50 Å2/ps. This study also investigates the structural transition from spherical to faceted gold nanoparticles upon heating. The temperatures of structural transition are in agreement with the experimental melting temperatures of gold nanoparticles with diameters ranging from 2 nm to 8 nm.
Highlights
Much attention has been paid to metal nanoparticles, owing to their unique thermodynamic, electrical, magnetic, optical, chemical and catalytic properties, which strongly depend on the particle size and geometries[1,2]
The kinetic Monte Carlo method can simulate a larger temporal step than the fine temporal step produced by the molecular dynamics method, which makes it suitable to study the long-time evolution of large nano-metal systems containing numerous atoms[14,15,16]
The reliability and accuracy of the kinetic Monte Carlo (kMC) simulation are determined by the calculation of all transition rates, which can be computed from the interatomic interaction and the energy barriers of transitions
Summary
Simulation of Atomic Diffusion and Structural Transition for Gold received: 18 April 2016 accepted: 04 July 2016 Published: 15 September 2016. By applying the lattice kinetic Monte Carlo simulation on gold films, we found that the atomic diffusion of Au on the Au(111) surface undergoes a late transition state with an energy barrier of about 0.2 eV and a prefactor between 40~50 Å2/ps. A developed pair interaction model that can handle atoms in different coordination environment such as at corners and edges is necessitated by the simulation of faceted metal nanoparticles. An interatomic interaction model distinguishing the atomic coordination number is developed and the calculation method of energy barriers depending on the location of the transition state is introduced. The coordination-averaged energies of Au atoms were derived and applied to study the diffusion of Au adatom on Au(111) and structural transition of gold nanoparticles.
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