Transcript Various types of multiscale modeling and simulation are studied in

Catalysis Center for Energy Innovation
Overview of Multiscale Modeling
Approach
Dion Vlachos
Univ. of Delaware
Catalysis Center for Energy Innovation
Bottom-up and Top-down Modeling:
Process Design and Catalyst Screening
Reviews: Chem. Eng. J. 90, 3 (2002); Chem. Eng. Sci. 59, 5559 (2004); Adv. Chem. Eng. 30, 1 (2005)
Catalysis Center for Energy Innovation
The 30,000 Miles Airview
Significant progress made
on method development
and testing
Field is maturing
Focus has been on
prototype problems
Complex systems have byand-large not been
studied
Perspecive: Vlachos, AIChE J. 58(5), 1314 (2012)
Catalysis Center for Energy Innovation
Hierarchy Enables Rapid Screening of
Chemistry, Fuels, and Catalysts
Accuracy, cost
Reactor scale:
Performance
Pseudo-homogeneous:
Ideal:
PFR, CSTR, etc. Transport correlations
Catalyst scale:
Reaction rate
Electronic scale:
Parameter estimation
Continuum:
MF-ODEs
Mesoscopic:
PDEs
Quantum-based
correlations:
BEPs, GA, LSRs
Discrete:
CG-KMC
Computational
Fluid Dynamics
(CFD)
Discrete:
KMC
Quantum:
ab initio, DFT, TST,
CPMD, QM/MM MD
Review: Salciccioli et al., Chem. Eng. Sci. 66, 4319 (2011)
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Toward High-throughput Computing:
Metal and Metal-like Catalysis
Linear
Scaling
Relations
(LSRs)
Group
Additivity
(GA)
Brønsted
Evans Polanyi
(BEP)
Microkinetic
Model
(MKM)
Thermochemistry via GA & LSRs
Reaction barriers and pre-exps via BEPs
Perform MKM
DFT-based, semi-empirical, or hierarchical
(screen with semi-empirical and refine via DFT)
Error analysis; Assessment of model predictions
Salciccioli et al., J. Phys. Chem. C , 114, 20155 (2010); J. Phys. Chem. C, 116, 1873 (2012)
Sutton and Vlachos, ACS Catal. 2, 1624 (2012); J. Catal. 297, 202 (2013)
Catalysis Center for Energy Innovation
The Kinetic Monte Carlo Approach
Metal
surface
k rxn   
transition
state
reactants
CO(gas) + OH
kB  T Q

e
h
Q rxn
products
‡
Potential
Energy
Surface
COOH
• Instead of simulating dynamics, KMC focuses on rare events
• Simulates reactions much faster than Molecular Dynamics
• Incorporates spatial information contrary to micro-kinetic models
Stamatakis and Vlachos, J. Chem. Phys. 134, 214115 (2011);
http://www.dion.che.udel.edu/downloads.php

E‡
k B T