Presentation is loading. Please wait.

Presentation is loading. Please wait.

Coarse-Grained Theory of Surface Nanostructure Formation Dimitri D. Vvedensky The Blackett Laboratory, Imperial College London Christoph A. Haselwandter.

Similar presentations


Presentation on theme: "Coarse-Grained Theory of Surface Nanostructure Formation Dimitri D. Vvedensky The Blackett Laboratory, Imperial College London Christoph A. Haselwandter."— Presentation transcript:

1 Coarse-Grained Theory of Surface Nanostructure Formation Dimitri D. Vvedensky The Blackett Laboratory, Imperial College London Christoph A. Haselwandter Department of Applied Physics, Caltech

2 Imperial College London

3 Outline Systems with many scales The coarse-graining road map Renormalization-group trajectories Transient effects and crossover Experimental realizations Extension to the submonolayer regime

4 Outline Systems with many scales The coarse-graining road map Renormalization-group trajectories Transient effects and crossover Experimental realizations Extension to the submonolayer regime

5 Multiscale Physics: Turbulence C. H. K. Williamson, Cornell (Source: http://www.efluids.com) Free gliding of delta-wing in water Fluorescent dye illuminated by laser Vortices in near field Turbulence in far field Both panels have same scale Energy cascades from large to small scales

6 Multiscale Physics: Fracture F. F. Abraham, D. Brodbeck, R. A. Rafey, and W. E. Rudge, Phys. Rev. Lett. 73, 272 (1994). 2D simulation of 10 6 - atom system Bond-breaking at crack tip Dislocation emission blunts crack tip Feed-back between atomic and continuum modes

7 Multiscale Physics: Critical Phenomena 2D Ising Model J. D. Noh, Chungham National University, Korea

8 Multiscale “Physics”: Medical Implants B. Kasemo, Surface Science 500, 656 (2002) Time Scale ns µm ms

9 Outline Systems with many scales The coarse-graining road map Renormalization-group trajectories Transient effects and crossover Experimental realizations Extension to the submonolayer regime

10 formulation Master & Chapman- Kolmogorov equations Lattice Langevin equation Hierarchy of equations KMC simulations Lattice model Macroscopic equation continuum variables renormalization-group (crossover, scaling, self-organization) analytic stable fixed point Chua et al., PRE 72, 051103 (2005), C. A. H. & D. D. V., PRE 76, 041115 (2007) Direct analysis/solution C. A. H. & D. D. V. PRL, EPL, PRE (2007, 2008) Coarse-Graining Road Map Continuum equation

11 Lattice-to-Continuum Method “Atomistic” Continuum Equation

12 Compare atomistic equation directly to computer simulations? Extract qualitative multiscale surface features via RG analysis… Continuum Equation for Random Deposition/Diffusion

13 The Multiscale Paradigm M. Scheffler, FHI–Berlin

14 Outline The coarse-graining road map Renormalization-group trajectories Transient effects and crossover Experimental realizations Extension to the submonolayer regime

15 Renormalization Group Transformations Real Space Momentum Space Original SystemCoarse GrainingRescaling

16 Renormalization-Group Equations Points along RG trajectory constitute a hierarchy of equations. RG “weeds out” terms that become irrelevant as the scale is increased, and absorbs their contributions into other terms.

17 Outline The coarse-graining road map Renormalization-group trajectories Transient effects and crossover Experimental realizations Extension to the submonolayer regime

18 Stable & Unstable Fixed Points

19 Initial Conditions & Crossover

20 Outline The coarse-graining road map Renormalization-group trajectories Transient effects and crossover Experimental realizations Extension to the submonolayer regime

21 Regimes of Growth D/F>>1. Typical MBE conditions. Initially, conserved Mullins-Herring. Submonolayer regime. D/F ≈ 1. Diffusion noise diminished in importance. Initially, Mullins-Herring. Al on silicone oil (Fang et al., Thin Solid Films 517, 3408 (2009)). D/F<<1. Growth dominated by shot noise.

22 Growth on Patterned Substrates. 1. H.-C. Kan et al., Phys. Rev. Lett. 92, 146101 (2004). KPZ cVLDS VLDS Moun d

23 Growth on Patterned Substrates. 2. H.-C. Kan et al., Phys. Rev. Lett. 92, 146101 (2004). ExperimentKPZcVLDS

24 Analysis from Initial Conditions

25 Outline The coarse-graining road map Renormalization-group trajectories Transient effects and crossover Experimental realizations Extension to the submonolayer regime

26 The Submonolayer Regime

27 Summary Continuum formulation that retains connection to atomistic processes Unifies a wide range of experimental scenarios Extension to submonolayer regime Large-scale morphologies on patterned substrates

28 Ongoing and Future Work Coarse-graining magnetohydrodynamics Coarse-grained molecular dynamics


Download ppt "Coarse-Grained Theory of Surface Nanostructure Formation Dimitri D. Vvedensky The Blackett Laboratory, Imperial College London Christoph A. Haselwandter."

Similar presentations


Ads by Google