Papers by Keyword: Radial Distribution Function (RDF)

Abstract: The mixing situation of Co atoms implanting onto Cu(001) substrate is investigated with regard to incident energy and substrate temperature by molecular dynamics. The results indicate that higher substrate temperature and/or incident energy will result in higher intermixing between the incident atoms and the substrate atoms. Furthermore, the value of the first peak of the radial distribution function (RDF) becomes lower and wider for the Co-Cu system as the substrate temperature and/or incident energy are increased.

Abstract: Developments of tetrahedral amorphous carbon (ta-C) films having low residual compressive stress are essential to extend the applicability of the films. The annealing of the ta-C films was known to be an effective way for the reduction the stress of the films. However, the effects of annealing on the atomic structure of ta-C films have not been fully understood. The atomic structure changes by the annealing were studied using molecular dynamics simulation. The simulation showed that the annealing caused an increase of the atomic volume of ta-C film, which explained the stress reduction partially. However, the tendency of the stress reduction was different to high and low stress films. The annealing substantially reduced the stresses of high stress films compared to those of low stress films. Atomic structure analysis showed that the reason for the asymmetric stress reduction resulted from the relaxation of highly distorted bonds that existed in as-deposited films.

Abstract: A three-dimensional model of molecular dynamics (MD) was employed to study the nanometric machining process of Si. The model included the utilization of the Morse potential function and the Tersoff potential function to simulate the interatomic force between atoms. By analysis of snapshots and local radial distribution function (RDF) during the various stages of the cutting process, amorphous phase transformation of chip and machined surface are observed, but no phase transformation of bulk. Chip volume change is observed due to the amorphous phase transformation. Dislocations around the tool and elastic recovery of the machined surface do not appear. The effects of surface adsorption on machined surface state have been studied on the basis of surface energy and surfaces hardness. Surface energy decreases and hardness increases by adsorption. Oxygen atoms adsorbed are on the machined surface and subsurface region.

Abstract: A three-dimensional model of molecular dynamics (MD) simulation was employed to study the generation process of nanometric machined surfaces of monocrystalline copper. The model included the utilization of the Morse potential function to simulate the interatomic force between Cu-C and Cu-Cu. By analyses of the MD simulation snapshots of the various stages of the nanometric cutting process and local radial distribution function (RDF), the structure of the bulk and the machined surface with no change and that of the chip with minimal change were observed. Potential energy had significant fluctuations due to generation and propagation of dislocations around the tool. The elastic recovery along the machined surface of the work material was observed after the tool passed. Because the state of machined surface was an important influence on the performance and the physical and chemical properties of product, the effects of surface relaxation on the machined surface state were investigated under the vacuum condition.