Coarse-grained kinetic Monte Carlo models: Complex lattices, multicomponent systems, and homogenization at the stochastic level

2008 ◽  
Vol 129 (18) ◽  
pp. 184101 ◽  
Author(s):  
Stuart D. Collins ◽  
Abhijit Chatterjee ◽  
Dionisios G. Vlachos
Keyword(s):  
Monte Carlo ◽  
Kinetic Monte Carlo ◽  
Coarse Grained ◽  
Multicomponent Systems

Kinetic Monte Carlo Method

2006 ◽  
Author(s):  
Vasily Bulatov ◽  
Wei Cai
Keyword(s):  
Monte Carlo ◽  
Kinetic Monte Carlo ◽  
Dislocation Core ◽  
Dislocation Motion ◽  
Coarse Grained ◽  
Solid Thin Films ◽  
Finite Set ◽  
And Migration ◽  
Dynamics Simulations ◽  
Straight Segments

The PN model discussed in the preceding chapter is a continuum approach that requires some atomistic input to account for non-linear interactions in the dislocation core. In this chapter, we introduce yet another continuum model that uses atomistic input for a different purpose. The kinetic Monte Carlo (kMC) model does not consider any details of the core structure but instead focuses on dislocation motion on length and time scales far greater than those of the atomistic simulations. The model is especially effective for diamond-cubic semiconductors and other materials in which dislocation motion is too slow to be observed on the time scale of molecular dynamics simulations. The key idea of the kMC approach is to treat dislocation motion as a stochastic sequence of discrete rare events whose mechanisms and rates are computed within the framework of the transition state theory. Built around its unit mechanisms, the kMC model simulates dislocation motion and predicts dislocation velocity as a function of stress and temperature. This data then can be used to construct accurate mobility functions for dislocation dynamics simulations on still larger scales (Chapter 10). In this sense, kMC serves as a link between atomistic models and coarse-grained continuum models of dislocations. The kMC approach is most useful in situations where the system evolves through a stochastic sequence of events with only a few possible event types. The method has been used in a wide variety of applications other than dislocations. For example, the growth of solid thin films from vapor or in solution is known to proceed through attachment and diffusion of adatoms deposited on the surface. Based on a finite set of unit mechanisms of the motion of adatoms, kMC models accurately describe the kinetics of growth and the resulting morphology evolution of the epitaxial films [95, 96, 97]. Similar kMC models have been applied to dislocation motion in crystals with high lattice resistance, such as silicon. In these materials, dislocations consist of long straight segments interspersed with atomic-sized kinks, depicted schematically in Fig. 9.1(a) as short vertical segments. As was explained in Section 1.3, dislocation motion proceeds through nucleation and migration of kink pairs and can be described well by a kMC model.

Multiscale modelling of charge transport in P3HT:DIPBI bulk heterojunction organic solar cells

2021 ◽  
Author(s):  
Tobias Koch ◽  
Jim-Martin Bachmann ◽  
Tobias Lettmann ◽  
Nikos Doltsinis
Keyword(s):  
Molecular Dynamics ◽  
Monte Carlo ◽  
Solar Cell ◽  
Charge Transport ◽  
Organic Solar Cells ◽  
Bulk Heterojunction ◽  
Kinetic Monte Carlo ◽  
Coarse Grained ◽  
Bulk Heterojunction Solar Cell ◽  
Kinetic Monte Carlo Simulations

Charge transport properties of a P3HT:DIPBI bulk heterojunction solar cell are modelled by kinetic Monte Carlo simulations based on a morphology obtained from coarse grained molecular dynamics. Different methods for...

Distinguishing the influence of structural and energetic disorder on electron transport in fullerene multi-adducts

2015 ◽  
Vol 2 (1) ◽  
pp. 113-119 ◽  
Author(s):  
Florian Steiner ◽  
Samuel Foster ◽  
Arthur Losquin ◽  
John Labram ◽  
Thomas D. Anthopoulos ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Monte Carlo ◽  
Electron Transport ◽  
Kinetic Monte Carlo ◽  
Structural Disorder ◽  
Coarse Grained ◽  
Monte Carlo Modeling ◽  
Energetic Disorder ◽  
Coarse Grained Molecular Dynamics

A combination of coarse-grained molecular dynamics and kinetic Monte-Carlo modeling shows that electron transport in fullerene multi-adducts is limited by energetic disorder due to different isomers rather than by structural disorder.

scholarly journals Slip Spring-Based Mesoscopic Simulations of Polymer Networks: Methodology and the Corresponding Computational Code

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1156 ◽  
Author(s):  
Grigorios Megariotis ◽  
Georgios Vogiatzis ◽  
Aristotelis Sgouros ◽  
Doros Theodorou
Keyword(s):  
Monte Carlo ◽  
Equation Of State ◽  
Kinetic Monte Carlo ◽  
Polymer Network ◽  
Polymer Networks ◽  
Test System ◽  
Helmholtz Energy ◽  
Coarse Grained ◽  
Crosslinked Polymer ◽  
Mesoscopic Simulations

In previous work by the authors, a new methodology was developed for Brownian dynamics/kinetic Monte Carlo (BD/kMC) simulations of polymer melts. In this study, this methodology is extended for dynamical simulations of crosslinked polymer networks in a coarse-grained representation, wherein chains are modeled as sequences of beads, each bead encompassing a few Kuhn segments. In addition, the C++ code embodying these simulations, entitled Engine for Mesoscopic Simulations for Polymer Networks (EMSIPON) is described in detail. A crosslinked network of cis-1,4-polyisoprene is chosen as a test system. From the thermodynamic point of view, the system is fully described by a Helmholtz energy consisting of three explicit contributions: entropic springs, slip springs and non-bonded interactions. Entanglements between subchains in the network are represented by slip springs. The ends of the slip springs undergo thermally activated hops between adjacent beads along the chain backbones, which are tracked by kinetic Monte Carlo simulation. In addition, creation/destruction processes are included for the slip springs at dangling subchain ends. The Helmholtz energy of non-bonded interactions is derived from the Sanchez–Lacombe equation of state. The isothermal compressibility of the polymer network is predicted from equilibrium density fluctuations in very good agreement with the underlying equation of state and with experiment. Moreover, the methodology and the corresponding C++ code are applied to simulate elongational deformations of polymer rubbers. The shear stress relaxation modulus is predicted from equilibrium simulations of several microseconds of physical time in the undeformed state, as well as from stress-strain curves of the crosslinked polymer networks under deformation.

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