Authors: A.V. Vasenkov, A.I. Fedoseyev, V.I. Kolobov, Ki-Ha Hong, H.S. Choi, K.H. Kim, J. Kim, H.S. Lee and J.K. Shin
Affilation: CFD Research Corporation, United States
Pages: 9 - 12
Keywords: multi-scale modeling, bridging disparate time and length scales, kinetic Monte Carlo, molecular dynamics, growth of carbon nanotubes
The current rapid development of nanotechnology has created a significant interest to predict the behavior of materials from the atomic to the engineering scales. However, it was found that such prediction is a very challenging problem since existing atomistic models are too slow, while mesoscopic and/or continuum codes are not capable of capturing nanoscale effects. This paper addresses this problem by introducing a Multi Scale Computational Framework (MSCF) which couples a reactor-scale module for gas/plasma-phase and surface processes, a Kinetic Monte Carlo (KMC) – FILM module for the growth of molecular structures, Molecular Dynamics (MD) NAMD module for the self-assembly of atoms into molecular structures, a “Gap-tooth” module for bridging reactor-scale and atomistic KMC simulations, and a “Coarse timestepper” module for coupling KMC and MD modeling. This framework works on length and time scales that are a million times disparate. The high efficiency was achieved due to the use of continuum model in large gaps where details of atomic motion are unimportant, while atomistic KMC-FILM and NAMD modeling was performed in tiny teeth where atoms self-assemble into molecular structures. The feasibility of MSCE was investigated for plasma-assisted growth of carbon nanotubes (CNTs). Dominant path for delivering the supply of carbon onto growing CNT surface and existence of two different modes during CNT growth are discussed.