Atomistic Simulations Of Silver Nanoparticles Based On Interatomic Potentials

Nanotechnology has a wide range of applications for its considerable prospects and values in preparing the nano-sized materials from one to three dimensions.Despite these nanostructured materials significantly exhibit different properties from their bulk phases due to the small-sized effect,which caused by the atoms with diverse coordination environment,there are still many limits in the experimental synthesis of Ag nanoparticles with a desirable control on size distribution and morphology.As an efficient research path,the atomic-scale simulations can not only explain the experimental results,but also provide atomistic pictures which can hardly obtained from limited experimental observations.To some extent,this obviously expands the research scope to go beyond the experimental conditions,not only on the size and dimensional scale,but also on the equilibrium to non-equilibrium states.This makes the exploration of some nanostructured materials available,especially the nanostructured materials which so far have not been successfully obtained or observed in experiments.So this kind of atomistic simulations can be taken as an important computational step to further research in the experimental lab.Based on the interatomic potentials,various atomic models of Ag nanoparticles were built to perform a series of atomistic simulations with regarding to the correlations linking with the size,shape and temperatures.In this paper,the following computations were consequently performed.Firstly,on the basis of the previous work of our group,the lattice inversion potentials(LI-Liu potential)were totally evaluated from the validity,transferability,and the cost of computational resource,compared with the traditional Sutton-Chen,the MEAM-1nn and the LJ+AT potentials.The advantages and disadvantages of LI-Liu potential were considered to check whether it can be used to provide the reasonable atomic configurations with diverse coordination environment in Ag nanoparticles or not.Secondly,the energy minimizations were performed to achieve the structural relaxation,from which the stable configurations of Ag nanoparticles with different sizes and shapes were obtained,and then the atomic coordination number,surface ratio and average bond length were used to describe the atomic structural details.The energy per atom was also used to estimate the stability of Ag nanoparticles as a function os size N.Thirdly,as an important side of atomistic simulations,the lattice dynamics calculations were also performed to show the properties related to the atomic vibrations.The phonon densities of states are presented to reveal the difference caused by the shapes and sizes of Ag nanoparticles.Futhermore,the lattice specific heat and Debye temperature were also obtained to exhibit the size and dimensional effects,and the fractal dimensions were put forward in terms of the high-temperature Dulong-Petit limit.Finally,the molecular dynamics simulations were used to explore the thermal stability of cubic and octahedral Ag nanoparticles with featured(100)and(111)surfaces respectively.The atomic structural evaluation was investigated within the temperature range 0-1200 K,the influence from the initial shapes and sizes were discussed in detail.During the annealing simulations,the different temperature variation periods were used to estimate whether the shapes of Ag nanoparticles can be controlled by adjusting the temperature or not.This may be taken as the important reference for future experimental process parameters.