Jan Willem Abraham

Molecular dynamics simulation of gold cluster growth during sputter deposition

We present a molecular dynamics simulation scheme that we apply to study the time evolution of the self-organized growth process of metalcluster assemblies formed by sputter-deposited gold atoms on a planar surface. The simulation model incorporates the characteristics of the plasma-assisted deposition process and allows for an investigation over a wide range of deposition parameters. It is used to obtain data for the cluster properties which can directly be compared with recently published experimental data for gold on polystyrene [M. Schwartzkopf et al., ACS Appl. Mater. Interfaces 7, 13547 (2015)]. While good agreement is found between the two, the simulations additionally provide valuable time-dependent real-space data of the surface morphology, some of whose details are hidden in the reciprocal-space scattering images that were used for the experimental analysis.

Quantum breathing mode of trapped systems in one and two dimensions

We investigate the quantum breathing mode (monopole oscillation) of trapped fermionic particles with Coulomb and dipole interaction in one and two dimensions. This collective oscillation has been shown to reveal detailed information on the many-particle state of interacting trapped systems and is thus a sensitive diagnostics for a variety of finite systems, including cold atomic and molecular gases in traps and optical lattics, electrons in metal clusters and in quantum confined semiconductor structures or nanoplasmas. An improved sum rule formalism allows us to accurately determine the breathing frequencies from the ground state of the system, avoiding complicated time-dependent simulations. In combination with the Hartree-Fock and the Thomas-Fermi approximations this enables us to extend the calculations to large particle numbers

Kinetic Monte Carlo Simulations of Cluster Growth and Diffusion in Metal-Polymer Nanocomposites

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Simulation of nanocolumn formation in a plasma environment

on the order of several million. Tracing the breathing frequency to large

Theory of the quantum breathing mode in harmonic traps and its use as a diagnostic tool.

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Quantum Breathing Mode of Interacting Particles in a One-dimensional Harmonic Trap

as a function of the coupling parameter of the system reveals a surprising difference of the asymptotic behavior of one-dimensional and two-dimensional harmonically trapped Coulomb systems.

Quantum Breathing Mode of Trapped Particles: From Nanoplasmas to Ultracold Gases

This chapter presents computer simulations of cluster growth and diffusion in metal-polymer nanocomposites based on the kinetic Monte Carlo method. The goal is to condense the crucial processes taking place during polymer metallization into a self-consistent simulation scheme which is able to reproduce and predict qualitative changes caused by variations of deposition conditions. The focus of this chapter lies on the discussion of the simulation model and the mathematical framework of kinetic Monte Carlo methods. The first section gives a brief overview over important physical aspects during metal-polymer nanocomposite formation. It is followed by a compact introduction into the theory of continuous-time Markov chains which is the mathematical foundation of the kinetic Monte Carlo method. In another section, the basic assumptions and simplifications of the simulation model are extensively discussed and physically motivated. The chapter closes with a discussion of simulation results of metal-polymer interface formation and co-deposition of metal and polymer. Yet, the intention of these simulations is not to provide a microscopic understanding of metal-polymer nanocomposites formation.

Recent progress in the theory and simulation of strongly correlated plasmas: phase transitions, transport, quantum, and magnetic field effects

Recent experiments and kinetic Monte Carlo (KMC) simulations [1,2] demonstrated that physical vapor codeposition of a metal alloy (Fe-Ni-Co) and a polymer (Teflon AF) can lead to self-organized growth of magnetic nanocolumns. While these experiments have been carried out with thermal sources, we analyze the feasibility of this process for the case of a sputtering source. For that purpose, we extend our previous simulation model by including a process that takes into account the influence of ions impinging on the substrate [3]. The simulation results predict that metal nanocolumn formation should be possible. Furthermore we show that the effect of ions, which create trapping sites for the metal particles, is an increased number of nanocolumns.