ReaxFF parameterization using Metropolis Monte Carlo …5/5 /department of mechanical engineering...
Transcript of ReaxFF parameterization using Metropolis Monte Carlo …5/5 /department of mechanical engineering...
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ReaxFF parameterizationusing Metropolis MonteCarlo algorithm
Eldhose Iype ([email protected])
S.V.NedeaEnergy Technology Group
December 2, 2014
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Parameterization of Reax force field
◮ Quantum Chemical (DFT) data is used to parameterize the forcefield
◮ A training data set is prepared which contains the followinginformations
• Atomic charges (Mulliken)• Equilibrium bond lengths• Equilibrium bond angles• Torsion angles• Energies of the DFT optimized geometries• Heat of formation
◮ Error in the force field is then calculated
Err(p1, p2, · · · pn) =
n∑
i=1
[
xi ,QM − xi ,ReaxFF
σi
]2
![Page 3: ReaxFF parameterization using Metropolis Monte Carlo …5/5 /department of mechanical engineering Overview How to set-up input files (geo,trainset.in)? Optimizing water force field,](https://reader035.fdocuments.us/reader035/viewer/2022071414/610dc4d56fea6145e06262cf/html5/thumbnails/3.jpg)
2/5
/department of mechanical engineering
Parameterization of Reax force field
◮ Quantum Chemical (DFT) data is used to parameterize the forcefield
◮ A training data set is prepared which contains the followinginformations
• Atomic charges (Mulliken)• Equilibrium bond lengths• Equilibrium bond angles• Torsion angles• Energies of the DFT optimized geometries• Heat of formation
◮ Error in the force field is then calculated
Err(p1, p2, · · · pn) =
n∑
i=1
[
xi ,QM − xi ,ReaxFF
σi
]2
![Page 4: ReaxFF parameterization using Metropolis Monte Carlo …5/5 /department of mechanical engineering Overview How to set-up input files (geo,trainset.in)? Optimizing water force field,](https://reader035.fdocuments.us/reader035/viewer/2022071414/610dc4d56fea6145e06262cf/html5/thumbnails/4.jpg)
2/5
/department of mechanical engineering
Parameterization of Reax force field
◮ Quantum Chemical (DFT) data is used to parameterize the forcefield
◮ A training data set is prepared which contains the followinginformations
• Atomic charges (Mulliken)• Equilibrium bond lengths• Equilibrium bond angles• Torsion angles• Energies of the DFT optimized geometries• Heat of formation
◮ Error in the force field is then calculated
Err(p1, p2, · · · pn) =
n∑
i=1
[
xi ,QM − xi ,ReaxFF
σi
]2
![Page 5: ReaxFF parameterization using Metropolis Monte Carlo …5/5 /department of mechanical engineering Overview How to set-up input files (geo,trainset.in)? Optimizing water force field,](https://reader035.fdocuments.us/reader035/viewer/2022071414/610dc4d56fea6145e06262cf/html5/thumbnails/5.jpg)
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Metropolis Monte Carlo (MMC) method
◮ Calculate the error of the starting force field, Errold
◮ Make a new proposition (move) for the parameters
◮ Calculate the error of the new force field, Errnew
◮ Calculate the difference in the Error, i.e.
∆Err = Errnew − Errold
◮ Accept the move with a probability given by,
P = min [1, exp (−β∆Err)] ,where, β =1
kBT
◮ Repeat the algorithm
![Page 6: ReaxFF parameterization using Metropolis Monte Carlo …5/5 /department of mechanical engineering Overview How to set-up input files (geo,trainset.in)? Optimizing water force field,](https://reader035.fdocuments.us/reader035/viewer/2022071414/610dc4d56fea6145e06262cf/html5/thumbnails/6.jpg)
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Error vs β for a Simulated Annealing run
0
1e+06
2e+06
3e+06
4e+06
5e+06
6e+06
7e+06
1e-05 0.0001 0.001
Err
or
β
Error vs β =1/(KBT)
![Page 7: ReaxFF parameterization using Metropolis Monte Carlo …5/5 /department of mechanical engineering Overview How to set-up input files (geo,trainset.in)? Optimizing water force field,](https://reader035.fdocuments.us/reader035/viewer/2022071414/610dc4d56fea6145e06262cf/html5/thumbnails/7.jpg)
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Overview
◮ How to set-up input files (geo,trainset.in)?
◮ Optimizing water force field, MMC at low temperature
◮ Simulated annealing
![Page 8: ReaxFF parameterization using Metropolis Monte Carlo …5/5 /department of mechanical engineering Overview How to set-up input files (geo,trainset.in)? Optimizing water force field,](https://reader035.fdocuments.us/reader035/viewer/2022071414/610dc4d56fea6145e06262cf/html5/thumbnails/8.jpg)
5/5
/department of mechanical engineering
Overview
◮ How to set-up input files (geo,trainset.in)?
◮ Optimizing water force field, MMC at low temperature
◮ Simulated annealing
![Page 9: ReaxFF parameterization using Metropolis Monte Carlo …5/5 /department of mechanical engineering Overview How to set-up input files (geo,trainset.in)? Optimizing water force field,](https://reader035.fdocuments.us/reader035/viewer/2022071414/610dc4d56fea6145e06262cf/html5/thumbnails/9.jpg)
5/5
/department of mechanical engineering
Overview
◮ How to set-up input files (geo,trainset.in)?
◮ Optimizing water force field, MMC at low temperature
◮ Simulated annealing