Molecular-dynamics study of the structural rearrangements of Cu and Au clusters softly deposited on a Cu(001) surface

Palacios, Francisco; Iñiguez, M. P.; López, M. J.; Alonso, J. A.

doi:10.1103/physrevb.60.2908

Cited by 61 publications

(30 citation statements)

References 35 publications

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“…These potentials, which are fitted to the experimental values of cohesive energy, lattice parameters and elastic constants, have been successfully applied in many works concerning clusters 27,28,29,30,31,32,33,34 and nanocrystalline materials. 11,23,35,36,37,38 The equations of motion in our simulations were integrated with the help of the velocity form of the Verlet algorithm 39 using a time-step h = 2 fs.…”

Section: A Generalmentioning

confidence: 99%

Vibrational properties of nanoscale materials: From nanoparticles to nanocrystalline materials

et al. 2003

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The vibrational density of states (VDOS) of nanoclusters and nanocrystalline materials are derived from molecular-dynamics simulations using empirical tight-binding potentials. The results show that the VDOS inside nanoclusters can be understood as that of the corresponding bulk system compressed by the capillary pressure. At the surface of the nanoparticles the VDOS exhibits a strong enhancement at low energies and shows structures similar to that found near flat crystalline surfaces. For the nanocrystalline materials an increased VDOS is found at high and low phonon energies, in agreement with experimental findings. The individual VDOS contributions from the grain centers, grain boundaries, and internal surfaces show that, in the nanocrystalline materials, the VDOS enhancements are mainly caused by the grain-boundary contributions and that surface atoms play only a minor role. Although capillary pressures are also present inside the grains of nanocrystalline materials, their effect on the VDOS is different than in the cluster case which is probably due to the inter-grain coupling of the modes via the grain-boundaries.

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Section: A Generalmentioning

confidence: 99%

Vibrational properties of nanoscale materials: From nanoparticles to nanocrystalline materials

et al. 2003

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“…Even though soft landing can be used to preserve size in cluster deposition experiments, the geometry of deposited clusters will differ from the geometry of gas phase clusters due to the interaction with the substrate [38,39]. In the present study, two-dimensional structures can be assumed for the deposited clusters because of their small size.…”

Section: The Soft Landing Processmentioning

confidence: 99%

Soft landing of size-selected clusters in rare gas matrices

Lau

Würth

Ehrke

et al. 2003

Low Temperature Physics

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Soft landing of mass selected clusters in rare gas matrices is a technique used to preserve mass selection in cluster deposition. To prevent fragmentation upon deposition, the substrate is covered with rare gas matrices to dissipate the cluster kinetic energy upon impact. Theoretical and experimental studies demonstrate the power of this technique. Besides STM, optical absorption, excitation, and fluorescence experiments, x-ray absorption at core levels can be used as a tool to study soft landing conditions, as will be shown here. X-ray absorption spectroscopy is also well suited to follow diffusion and agglomeration of clusters on surfaces via energy shifts in core level absorption.

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“…Clearly, more com plex models similar to the ab initio method are more realistic, but it turns out to be just impossible to simu late clusters consisting of several hundred or thousand atoms by this method even in the current state of the art of computer technology. On the other hand, the potentials developed by Cleri and Rosato [21] were successfully applied in a number of cluster studies [22][23][24][25][26][27][28][29][30][31][32] and are currently among the main potentials for calculating the properties of metallic clusters.…”

Section: The Simulation Techniquementioning

confidence: 99%

Molecular-dynamics simulation of the heat capacity for nickel and copper clusters: Shape and size effects

Гафнер

Redel

Gafner

2012

J. Exp. Theor. Phys.

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We have investigated the heat capacity of ideal Cu and Ni fcc clusters with diameters from 2 to 6 nm in the temperature range 200-800 K by the molecular dynamics method using a modified tight binding potential. Our analysis has shown consistency with the experimental results at temperatures of 200-300 K. The data obtained are also indicative of several regularities that are in agreement with the analytical calcula tions. We have concluded from the results of our computer simulations that the heat capacity in the case of isolated free clusters can exceed that of a bulk material, with this difference decreasing as the nanoparticle grows proportionally to the reduction in the fraction of surface atoms. The excess of the heat capacity for ideal copper and nickel nanoclusters with D = 6 nm at T = 200 K has been found to be 10% and 13%, respectively. Consequently, the large heat capacities of copper and nickel nanostructures observed in some real experi ments cannot be related to the characteristics of free clusters. We hypothesize that these properties of a nano material depend on the degree of agglomeration of its constituent particles, i.e., the surfaces and interphase boundaries of interconnected nanoclusters can have a strong effect. To test this hypothesis, we took nickel and copper clusters of various sizes (4000-7200 atoms) produced through the simulation of condensation from the gas phase. At high temperatures, we failed to adequately assess the role of the interphase boundaries in calculating the heat capacity of nanoparticles. The reason was the mass diffusion of Ni or Cu atoms to impart an energetically more favorable shape and structure to the synthesized clusters. At low temperatures, the heat capacity of such clusters exceeded that of clusters with an ideal shape and structure by a value from 3.2% to 10.6%. We have concluded that the Ni and Cu clusters produced in real experiments cannot be applied in devices using the thermal energy of such clusters without a preliminary optimization stage, because their external shape and interior structure are nonideal.

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Molecular-dynamics study of the structural rearrangements of Cu and Au clusters softly deposited on a Cu(001) surface

Cited by 61 publications

References 35 publications

Vibrational properties of nanoscale materials: From nanoparticles to nanocrystalline materials

Vibrational properties of nanoscale materials: From nanoparticles to nanocrystalline materials

Soft landing of size-selected clusters in rare gas matrices

Molecular-dynamics simulation of the heat capacity for nickel and copper clusters: Shape and size effects

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