6. ReaxFF Models

6.1. Introduction

The Reactive Force Field (ReaxFF) replaces fixed bond topologies of classical force fields with the concept of bond order to simulate bond breaking/formation of chemical reactions. Originally conceived for hydrocarbons in the gas phase [1], ReaxFF has been extended to a wide range of applications [2].


Danger

Just because a ReaxFF potential is available with the atoms for your intented application, it DOES NOT mean it is transferable if the training set did not include configurations similar to your intented application. For example, there are many potentials with C/H/O/N atoms but not all have the pi-bond parameters trained so a benzene molecule might behave in a completely unphysical manner. You need to consult the original journal article (doi links below) together with the supplementary materials to confirm the transferability of a given ReaxFF potential to your application.

The Potential Energy Surface (PES) is an insanely immense mathematical object. PES of a system with N atoms doesn’t have N points, it has 3N dimensions! The odds are infinitesimal that someone else visited the same tiny slice of subspace you’re interested in and made a Machine-Learning Inter-Atomic-Potential (ML-IAP) or a Reax Force Field (FF) for you already. Stop looking for potentials from somewhere else, except to practice and learn to maybe get close to what you’re doing. For original research there’s no way around having to generate your own DFT and/or experimental data to train a new MLIAP or FF. This is the purpose of FitSNAP-ReaxFF.

ReaxFF in LAMMPS [3] supports three charge equilibration methods to represent the dynamics of electron density:

  • Charge Equilibration (QEq) [4][5]

  • Atom-Condensed Kohn-Sham DFT to second order (ACKS2) [6][7]

  • Charge Transfer and Polarization in Equilibrium (QTPIE) [8]

while fixed partial charges in classical force fields (eg. CHARMM) do not. FitSNAP-ReaxFF enables retraining of legacy ReaxFF QEq potentials for ACKS2 and QTPIE, including optimization of the bond_softness, chi, eta, gamma, bcut_acks2, and gauss_exp parameters.



6.2. ReaxFF functional form

The ReaxFF overall system energy is expressed as the sum:

\[\begin{split}E_{system} & = E_{bond} + E_{lp} + E_{over} + E_{under} + E_{val} + E_{pen} + E_{coa} + E_{C2}\\[.6em] & \qquad + E_{triple} + E_{tors} + E_{conj} + E_{Hbond} + E_{vdWaals} + E_{Coulomb}\end{split}\]

Details for each term:

  • Bond order/energy

  • Lone pair energy

  • Overcoordination

  • Undercoordination

  • Valence Terms (Angle energy, Penalty energy, Three-body conjugation term)

  • Correction for C2

  • Triple bond energy correction

  • Torsion Terms (Torsion rotation barriers, Four body conjugation term)

  • Hydrogen bond interactions

  • Nonbonded interactions (van der Waals, Coulomb)

are presented in the Supporting Information of A ReaxFF Reactive Force Field for Molecular Dynamics Simulations of Hydrocarbon Oxidation by Chenoweth, van Duin, Goddard (2008).



6.3. ReaxFF LAMMPS commands

where (/kk) denotes LAMMPS commands available in KOKKOS package.

Note

KOKKOS version of ReaxFF with -k on t 1 -sf kk is always used by FitSNAP-ReaxFF.

“IMO anyone and everyone should be using the KOKKOS version of ReaxFF. Not only is it more memory robust and will never have these hbondchk errors, it is also faster on CPUs, at least in most cases that I’ve benchmarked, or same speed at the very least.”
– Stan Moore (2024/10) on MatSci.org:
Lammps hbondchk failed.
“I highly suggest using the KOKKOS package for ReaxFF, works in serial for CPUs too.”
– Stan Moore (2024/10) on MatSci.org:
Segmentation fault: address not mapped to object at address 0xc2cfb87c.
“You could also try the KOKKOS version which doesn’t use the safezone, mincap, and minhbonds factors which can bloat the memory if you set them too high.”
– Stan Moore (2025/01) on MatSci.org:
Possible memory problem with Reaxff when the total atom number increased.


6.4. Fitting ReaxFF parameters

If a ReaxFF potential is not available for your intented application, then you can fit new parameters with FitSNAP-ReaxFF from DFT training data. FitSNAP-ReaxFF is based on the Covariance Matrix Adaptation Evolution Strategy (CMAES) optimization algorithm as implemented by the pycma python package. CMAES finds a minimum \(x \in \mathbb{R}^n\) of an objective function \(f(x)\). In FitSNAP-ReaxFF, the objective function minimized is the Sum of Squared Errors (SSE) between DFT reference data and predicted energy/forces given current values of parameters to be optimized.

The FitSNAP-ReaxFF workflow is fundamentally different than FitSNAP but relies on the same underlying infrastructure:

FitSNAP (SNAP/PACE/…)

Two separate phases after scraping data: (i) process_configs() to calculate descriptors and (ii) perform_fit() to solve for optimal coefficients.

FitSNAP-ReaxFF

One integrated phase: perform_fit() consists of a loop where process_configs() runs in parallel at each step of the fitting algorithm. During this loop, a population of popsize candidate parameters is refined until the CMAES algorithm meets a termination criteria.

You can start a FitSNAP-ReaxFF optimization with a potential file from reaxff/potentials/reaxff-<AUTHOR><YEAR>.ff (see below for full list bundled with FitSNAP-ReaxFF). You can also start with any other valid ReaxFF potential file (with the exception of eReaxFF and LG dispersion correction), or FIXME: restart from a previously optimized potential.

N2_ReaxFF example

Let’s start with a simple example related to the nitrogen molecule example of INQ, a modern clean-slate C++/CUDA open source (TD)DFT package from LLNL. DFT reference data can also be obtained from Quantum Espresso (QE), Vienna Ab initio Simulation Package (VASP), literature, online databases,…

First, training data is computed using INQ with PBE functional and saved to JSON/N2/N2*.json:

examples/N2_ReaxFF/N2_ReaxFF-bond-scan.py

from fitsnap3lib.parallel_tools import ParallelTools
from fitsnap3lib.io.input import Config
from fitsnap3lib.calculators.inq import INQ
import json
import numpy as np

bond_scan = [{
    "Positions":[[-d/2,0.0,0.0], [d/2,0.0,0.0]], 
    "AtomTypes":['N','N']
    } for d in np.arange(0.9,1.51,.05)]

settings = { "CALCULATOR": {
    "calculator": "INQ", "energy": 1, "force": 1, "dipole": 1 
}}

pt = ParallelTools()
config = Config(pt, settings)
inq = INQ('inq', pt, config)
inq.process_configs(bond_scan)

for i, b in enumerate(bond_scan):
    with open(f'JSON/N2/N2_{i}.json', 'w') as json_file:
        json.dump({"Dataset": {"Data": b}}, json_file)

Second, a FitSNAP-ReaxFF optimization with input scripts N2_ReaxFF-<CHARGE_FIX>.in:

examples/N2_ReaxFF/N2_ReaxFF-qeq.in
[REAXFF]
potential      = reaxff-wood2014.ff
parameters     = BND.N.N.p_bo1 BND.N.N.p_bo2 BND.N.N.p_bo3 BND.N.N.p_bo4 BND.N.N.p_bo5 BND.N.N.p_bo6
                 BND.N.N.p_be1 BND.N.N.p_be2 
                 BND.N.N.De_s BND.N.N.De_p BND.N.N.De_pp
                 BND.N.N.p_ovun1

[CALCULATOR]
calculator     = LAMMPSREAXFF
charge_fix     = fix 1 all qeq/reaxff 1 0.0 10.0 1.0e-6 reaxff maxiter 500
energy         = .5
force          = 0
dipole         = .5

[SOLVER]
solver         = CMAES
popsize        = 10
sigma          = 0.1

[SCRAPER]
scraper        = JSON

[PATH]
dataPath       = JSON

[OUTFILE]
potential      = reaxff-n2-qeq.ff

[GROUPS]
group_sections = name training_size
group_types    = str float
N2-PBE         = 1.0

Third, potential energy computed along the bond scan \(\text{N}\!\equiv\!\text{N}\) by running LAMMPS with potentials

  • reaxff-wood2014.ff

  • reaxff-N2_ReaxFF-qeq.ff

  • reaxff-N2_ReaxFF-acks2.ff

  • reaxff-N2_ReaxFF-qtpie.ff

is compared to QM training data with matplotlib and saved to N2_ReaxFF.png:

_images/N2_ReaxFF.png

6.4.1. FitSNAP-ReaxFF input script

Compared to linear and nonlinear models, the input script for ReaxFF models needs:

  • [REAXFF] section instead of [BISPECTRUM] or [ACE] section

  • calculator = LAMMPSREAXFF instead of LAMMPSSNAP, LAMMPSPACE, …

  • solver = CMAES instead of eg. SVD, PYTORCH, …

[REAXFF] section

  • potential path of initial ReaxFF potential file

  • parameters strings separated by spaces with format <BLOCK>.<ATOM_1>...<ATOM_N>.<NAME>:

    • GEN.name for atom parameters

    • ATM.C.name for atom parameters

    • BND.C.H.name for bond parameters

    • OFD.C.H.name for off-diagonal parameters

    • ANG.C.H.O.name for angle parameters

    • TOR.C.H.O.N.name for torsion parameters

    • HBD.C.H.O.name for hydrogen-bond parameters

    where name is LAMMPS implementation parameter name (which might be different than other ReaxFF implementations commonly seen in comments of potential files)

BlockPositionNameDescriptionCategoryEq. [15]
GENR1p_boc1Overcoordination parameterExpert4c
GENR2p_boc2Overcoordination parameterExpert4d
GENR3p_coa2Valency angle conjugation parameterExpert15
GENR4p_trip4Triple bond stabilization parameterExpert20
GENR5p_trip3Triple bond stabilization parameterExpert20
GENR6k_c2C2-correctionExpert19
GENR7p_ovun6Undercoordination parameterExpert12
GENR8p_trip2Triple bond stabilization parameterExpert20
GENR9p_ovun7Undercoordination parameterExpert12
GENR10p_ovun8Undercoordination parameterExpert12
GENR11p_trip1Triple bond stabilization energyExpert20
GENR12nonb_low,swaLower Taper-radiusDoNotOptimize21
GENR13R_cutUpper Taper-radiusDoNotOptimize21
GENR14p_fe1Fe dimer correctionDoNotOptimize6a
GENR15p_val6Valency undercoordinationExpert13c
GENR16p_lp1Valency angle/lone pair parameterExpert8
GENR17p_val9Valency angle parameterExpert13f
GENR18p_val10Valency angle parameterExpert13g
GENR19p_fe2Fe dimer correctionDoNotOptimize6a
GENR20p_pen2Double bond/angle parameterExpert14a
GENR21p_pen3Double bond/angle parameter: overcoordExpert14b
GENR22p_pen4Double bond/angle parameter: overcoordExpert14b
GENR23p_fe3Fe dimer correctionDoNotOptimize6a
GENR24p_tor2Torsion/BO parameterExpert16b
GENR25p_tor3Torsion overcoordinationExpert16c
GENR26p_tor4Torsion overcoordinationExpert16c
GENR28p_cot2ConjugationExpert17b
GENR29p_vdW1VdW shieldingExpert23b
GENR30cutoff*100Cutoff for bond order (* 100)Expert3a,b
GENR31p_coa4Valency angle conjugation parameterExpert15
GENR32p_ovun4Overcoordination parameterExpert11b
GENR33p_ovun3Overcoordination parameterExpert11b
GENR34p_val8Valency/lone pair parameterExpert13d
GENR35X_softACKS2 softness parameterExpert25
GENR39p_coa3Valency angle conjugation parameterExpert15
ATMR1C1r_sσ-bond covalent radiusStandard2
ATMR1C2valencyValencyDoNotOptimize3a,4b,5,9a
ATMR1C3massAtomic massDoNotOptimize9a
ATMR1C4r_vdwvan der Waals radiusExpert23a
ATMR1C5epsilonvan der Waals dissociation energyExpert23a
ATMR1C6gammaValence orbital exponent (QEQ, ACKS2, QTPIE)Expert24
ATMR1C7r_piπ-bond covalent radiusStandard2
ATMR1C8valency_eNumber of valence electronsDoNotOptimize7,8,9
ATMR2C1alphavan der Waals parameterExpert23b
ATMR2C2gamma_wvan der Waals shieldingExpert23b
ATMR2C3valency_bocValency for 1, 3-BO correctionDoNotOptimize16c,13c
ATMR2C4p_ovun5Undercoordination energyExpert12
ATMR2C5gauss_expGaussian orbital exponent (QTPIE)Expert26
ATMR2C6chiElectronegativity [always eV] (QEQ, ACKS2, QTPIE)Expert24,25
ATMR2C7etaAtomic hardness [always eV] (QEQ, ACKS2, QTPIE)Expert24,25
ATMR2C8p_hbondDonor or acceptor switch in H-bondsDoNotOptimizen/a
ATMR3C1r_pi_piπ-π-bond covalent radiusStandard2
ATMR3C2p_lp2Lone pair energyExpert10
ATMR3C3n/aAtomic heat of formationDoNotOptimizen/a
ATMR3C4b_o_131Bond order correctionExpert4e,f
ATMR3C5b_o_132Bond order correctionExpert4e,f
ATMR3C6b_o_133Bond order correctionExpert4e,f
ATMR3C7bcut_acks2Atomic softness cutoff parameter (ACKS2)Expert25
ATMR4C1p_ovun2Valence angle parameterExpert12
ATMR4C2p_val3Valence angle parameterExpert13b,13a
ATMR4C4valency_valNumber of lone pairsDoNotOptimize3b
ATMR4C5p_val5Valence angle parameterExpert13b
ATMR4C6rcore2Inner wall vdW repulsion parameterExpert23c
ATMR4C7ecore2Inner wall vdW repulsion parameterExpert23c
ATMR4C8acore2Inner wall vdW repulsion parameterExpert23c
BNDR1C1De_sσ-bond dissociation energyStandard6,11a
BNDR1C2De_pπ-bond dissociation energyStandard6
BNDR1C3De_ppπ-π-bond dissociation energyStandard6
BNDR1C4p_be1Bond energy parameter coefficientStandard6
BNDR1C5p_bo5π-π-bond parameter coefficientStandard2
BNDR1C6v13cor1,3-Bond order correctionDoNotOptimize3b
BNDR1C7p_bo6π-π-bond order exponentStandard2
BNDR1C8p_ovun1Overcoordination penaltyStandard11a
BNDR2C1p_be2Bond energy parameter exponentStandard6
BNDR2C2p_bo3π-bond order parameter coefficientStandard2
BNDR2C3p_bo4π-bond order parameter exponentStandard2
BNDR2C5p_bo1σ-bond order coefficientStandard2
BNDR2C6p_bo2σ-bond order exponentStandard2
BNDR2C7ovcUncorrected BO overcoordinationDoNotOptimize3a
OFDR1C1DVdW energyExpert23a
OFDR1C2r_vdWVdW radiusExpert23a
OFDR1C3alphaVdW parameterExpert23a
OFDR1C4r_sσ-bond lengthStandard2
OFDR1C5r_pπ-bond lengthStandard2
OFDR1C6r_ppπ-π-bond lengthStandard2
ANGR1C1theta_00180o-(equilibrium angle)Standard13g
ANGR1C2p_val1Valence angle parameterStandard13a
ANGR1C3p_val2Valence angle parameterStandard13a
ANGR1C4p_coa1Valence conjugationExpert15
ANGR1C5p_val7UndercoordinationExpert13c
ANGR1C6p_pen1Penalty energyExpert14b,14a
ANGR1C7p_val4Valence angle parameterExpert13b
TORR1C1V1V1-torsion barrierStandard16a
TORR1C2V2V2-torsion barrierStandard16a
TORR1C3V3V3-torsion barrierStandard16a
TORR1C4p_tor1Torsion angle parameterStandard16a
TORR1C5p_cot1Conjugation energyExpert17a
HBDR1C1r0_hbHydrogen bond equilibrium distanceStandard18
HBDR1C2p_hb1Hydrogen bond energyStandard18
HBDR1C3p_hb2Hydrogen bond/bond orderExpert18
HBDR1C4p_hb3Hydrogen bond parameterExpert18

Note

reaxff/tools/reaxff-format-ff.py properly reformats a ReaxFF potential file (eg. copy/pasted from journal articles) together with LAMMPS implementation parameter names in comment fields.

[CALCULATOR] section

  • calculator must be LAMMPSREAXFF for FitSNAP-ReaxFF

  • charge_fix charge equilibration fix command, eg:

    • (a) fix 1 all qeq/reaxff 1 0.0 10.0 1.0e-6 reaxff

    • (b) fix 1 all acks2/reaxff 1 0.0 10.0 1.0e-6 reaxff maxiter 500

    • (c) fix 1 all qtpie/reaxff 1 0.0 10.0 1.0e-6 reaxff exp.qtpie

    • fix ID (1 in examples a-c), can only contain alphanumeric characters and underscores to be valid in LAMMPS

  • energy turn on 1 or off 0 energy fitting

  • force turn on 1 or off 0 force fitting

  • stress ignored in FitSNAP-ReaxFF

  • dipole turn on 1 or off 0 dipole fitting

Note

Stress fitting is not supported in FitSNAP-ReaxFF, only energy = 1 and force = 1 are available.

[SOLVER] section

[SCRAPER] section

  • same as FitSNAP

[PATH] section

  • same as FitSNAP

[OUTFILE] section

  • potential path of optimized ReaxFF potential file

  • output_style not applicable because output_style=REAXFF implied by REAXFF section

[REFERENCE] section

  • not applicable in FitSNAP-ReaxFF

Note

FitSNAP-ReaxFF only supports units real and atom_style charge.

[GROUPS] section

  • same as FitSNAP


6.5. Available ReaxFF potentials

Historical serial Fortran 77 force fields (no longer compatible and not available)

Branch

Atoms

Filename

Source

combustion

C / H

n/a

van Duin et al.[1]

6.5.1. Combustion Branch

Available COMBUSTION force fields in LAMMPS

Branch

Atoms

Filename (LAMMPS)

Filename (SCM)

Source

combustion

Au/S/C/H

reaxff-jarvi2011.ff

AuSCH_2011.ff

Järvi et al.[9]

combustion

C

reaxff-srinivasan2015.ff

C.ff

Srinivasan et al.[10]

combustion

C/H

reaxff-mao2017.ff

CH_aromatics.ff

Mao et al.[11]

combustion

C/H/B/N

reaxff-pai2016.ff

CBN.ff

Pai et al.[12]

combustion

C/H/Na

reaxff-hjertenaes2016.ff

CHNa.ff

Hjertenæs et al.[13]

combustion

C/H/O

reaxff-ashraf2017.ff

CHO-2016.ff

Ashraf and Van Duin[14]

combustion

C/H/O

reaxff-chenoweth2008a.ff

CHO.ff

Chenoweth et al.[15]

combustion

C/H/O/Ba/Zr/Y

reaxff-vanduin2008.ff

BaYZrCHO.ff

Van Duin et al.[16]

combustion

C/H/O/N

reaxff-strachan2003.ff

n/a

Strachan et al.[17]

FIXME

C/H/O/N

reaxff-budzien2009.ff

n/a

Budzien et al.[18]

FIXME

C/H/O/N/S

reaxff-mattsson2010.ff

n/a

Mattsson et al.[19]

FIXME

C/H/O/N/S/F/Pt/Cl/Ni/X

reaxff-singh2013.ff

n/a

Singh et al.[20]

combustion

C/H/O/N/S/Si

reaxff-liu2011.ff

dispersion/CHONSSi-lg.ff

Liu et al.[21]

combustion

C/H/O/N/S/Si

reaxff-zhang2009.ff

HE2.ff

Zhang et al.[22]

combustion

C/H/O/N/S/Si/Ge

reaxff-psofogiannakis2016.ff

CHONSSiGe.ff

Psofogiannakis and Van Duin[23]

combustion

C/H/O/N/S/Si/Na/P

reaxff-zhang2014.ff

CHONSSiNaP.ff

Zhang et al.[24]

combustion

C/H/O/N/S/Si/Pt/Zr/Ni/Cu/Co

reaxff-nielson2005.ff

CHONSSiPtZrNiCuCo.ff

Nielson et al.[25]

combustion

C/H/O/N/S/Si/Pt/Ni/Cu/Co/Zr/Y/Ba

reaxff-merinov2014.ff

CHONSSiPtNiCuCoZrYBa.ff

Merinov et al.[26]

combustion

C/H/O/N/S/Si/Pt/Zr/Ni/
Cu/Co/He/Ne/Ar/Kr/Xe

reaxff-kamat2010.ff

CHONSSiPtZrNiCuCoHeNeArKrXe.ff

Kamat et al.[27]

combustion

C/H/O/N/Si/S

reaxff-kulkarni2013.ff

SiONH.ff

Kulkarni et al.[28]

combustion

C/H/O/S

reaxff-mueller2016.ff

Mue2016.ff

Müller and Hartke[29]

combustion

C/H/O/S

reaxff-komissarov2021.ff

n/a

Komissarov et al.[30]

combustion

C/H/O/S/F/Cl/N

reaxff-wood2014.ff

CHOSFClN.ff

Wood et al.[31]

combustion

C/H/Pt

reaxff-sanz2008.ff

PtCH.ff

Sanz-Navarro et al.[32]

combustion

C/H/O/Si

reaxff-chenoweth2005.ff

PDMSDecomp.ff

Chenoweth et al.[33]

FIXME

H/O/Au

reaxff-joshi2010.ff

n/a

Joshi et al.[34]

combustion

Co

reaxff-zhang2014b.ff

Co.ff

Zhang et al.[35]

combustion

H/O/N/B

reaxff-weismiller2010.ff

Ab.ff

Weismiller et al.[36]

combustion

Li/S

reaxff-islam2015.ff

LiS.ff

Islam et al.[37]

combustion

Ni/C/H

reaxff-mueller2010.ff

NiCH.ff

Mueller et al.[38]

combustion

O/Pt

reaxff-fantauzzi2014.ff

OPt.ff

Fantauzzi et al.[39]

combustion

Pd/H

reaxff-senftle2014.ff

PdH.ff

Senftle et al.[40]

combustion

Si/C/O/H/N/S

reaxff-newsome2012.ff

SiC.ff

Newsome et al.[41]

combustion

V/O/C/H

reaxff-chenoweth2008b.ff

VOCH.ff

Chenoweth et al.[42]

6.5.2. Independent Branch

Available INDEPENDENT force fields in LAMMPS

Branch

Atoms

Filename (LAMMPS)

Filename (SCM)

Source

independent

C/H/Ar/He/Ne/Kr

reaxff-yoon2016.ff

CHArHeNeKr.ff

Yoon et al.[43]

independent

C/H/Fe

reaxff-islam2016.ff

CHFe.ff

Islam et al.[44]

independent

C/H/Ga
C/H/In
reaxff-rajabpour2021a.ff
reaxff-rajabpour2021b.ff
GaCH-2020.ff
InCH-2020.ff

Rajabpour et al.[45]

independent

C/H/O/Ge

reaxff-nayir2018.ff

CHOGe.ff

Nayir et al.[46]

independent

C/H/O/Li/Al/Ti/P

reaxff-shin2018.ff

CHOLiAlTiP.ff

Shin et al.[47]

independent

C/H/O/N/B/Al/Si/Cl

reaxff-uene2024.ff

CHONBAlSiCl.ff

Uene et al.[48]

independent

C/H/O/N/S/Mg/P/Na/Cu/Cl/Ti/X

reaxff-hou2022.ff

CHONSMgPNaCuClTi.ff

Hou et al.[49]

independent

C/H/O/N/S/Si

reaxff-soria2018.ff

CHONSSi.ff

Soria et al.[50]

independent

C/H/O/N/S/Si/Ge/Ga/Ag

reaxff-niefind2024.ff

CHONSSiGeGaAg.ff

Niefind et al.[51]

independent

C/H/O/N/S/Zr

reaxff-dwivedi2020.ff

CHONSZr.ff

Dwivedi et al.[52]

independent

C/H/O/N/Si

reaxff-wang2020.ff

CHONSi.ff

Wang et al.[53]

independent

C/H/O/S/Cu/Cl/X

reaxff-yeon2018.ff

CuSCH.ff

Yeon et al.[54]

independent

C/H/O/S/Mo/Ni/Au/Ti

reaxff-mao2022.ff

CHOSMoNiAuTi.ff

Mao et al.[55]

independent

Cu/Zr

reaxff-huang2019.ff

CuZr.ff

Huang et al.[56]

independent

H/O/N/Si/F

reaxff-kim2021.ff

HONSiF.ff

Kim et al.[57]

independent

H/O/Si/Al/Li

reaxff-ostadhossein2016.ff

HOSiAlLi.ff

Ostadhossein et al.[58]

independent

H/S/Mo

reaxff-ostadhossein2017.ff

HSMo.ff

Ostadhossein et al.[59]

independent

I/Br/Pb/Cs

reaxff-pols2024.ff

IBrPbCs.ff

Pols et al.[60]

independent

I/Pb/Cs/X

reaxff-pols2021.ff

CsPbI.ff

Pols et al.[61]

independent

Li/Si/C

reaxff-olou2023.ff

LiSiC.ff

Olou’ou Guifo et al.[62]

independent

Mg/O

reaxff-fiesinger2023.ff

MgO.ff

Fiesinger et al.[63]

independent

Ni/Al

reaxff-du2023.ff

NiAl.ff

Du et al.[64]

independent

Ni/Cr

reaxff-shin2021.ff

NiCr.ff

Shin et al.[65]

independent

Ru/H

reaxff-onwudinanti2022.ff

RuH.ff

Onwudinanti et al.[66]

independent

Ru/N/H

reaxff-kim2018.ff

RuNH.ff

Kim et al.[67]

independent

Si/Al/Mg/O

reaxff-yeon2021.ff

SiAlMgO.ff

Yeon et al.[68]

independent

Si/O/H

reaxff-nayir2019.ff

SiOHv2.ff

Nayir et al.[69]

independent

W/S/H/Al/O

reaxff-nayir2021.ff

WSHAlO.ff

Nayir et al.[70]

independent

Zr/Y/O/H

reaxff-mayernick2010.ff

ZrYOHVac.ff

Mayernick et al.[71]

independent

Zr/Y/O/Ni/H

reaxff-liu2019.ff

ZrYONiH.ff

Liu et al.[72]

6.5.3. Water Branch

Available WATER force fields in LAMMPS

Branch

Atoms

Filename (LAMMPS)

Filename (SCM)

Source

water

Al/C/H/O

reaxff-hong2016.ff

AlCHO.ff

Hong and Van Duin[73]

water

C/H/O/Al/Ge/X

reaxff-zheng2017.ff

CHOAlGeX.ff

Zheng et al.[74]

water

C/H/O/Ca/Si/X

reaxff-manzano2012.ff

CaSiOH.ff

Manzano et al.[75]

water

C/H/O/Cs/K/Na/Cl/I/F/Li

reaxff-fedkin2019.ff

CHOCsKNaClIFLi.ff

Fedkin et al.[76]

water

C/H/O/Fe

reaxff-aryanpour2010.ff

FeOCHCl.ff

Aryanpour et al.[77]

water

C/H/O/Fe/Al/Ni/Cu/S/Cr

reaxff-shin2015.ff

CHOFeAlNiCuSCr.ff

Shin et al.[78]

water

C/H/O/Fe/Al/Ni/Cu/S/Cr

reaxff-tavazza2015.ff

CHOFeAlNiCuSCr_v3.ff

Tavazza et al.[79]

water

C/H/O/N

reaxff-rahaman2011.ff

Glycine.ff

Rahaman et al.[80]

water

C/H/O/N

reaxff-trnka2018.ff

n/a

Trnka et al.[81]

water

C/H/O/N

reaxff-kowalik2019.ff

CHON-2019.ff

Kowalik et al.[82]

water

C/H/O/N/S/Fe

reaxff-moerman2021.ff

CHONSFe.ff

Moerman et al.[83]

water

C/H/O/N/S/Mg/P/Na/Cu

reaxff-huang2013.ff

CuBTC.ff

Huang et al.[84]

water

C/H/O/N/S/Mg/P/Na/Cu/Cl

reaxff-monti2013a.ff

CHONSMgPNaCuCl.ff

Monti et al.[85]

water

C/H/O/N/S/Mg/P/Na/Cu/Cl

reaxff-monti2013b.ff

CHONSMgPNaCuCl_v2.ff

Monti et al.[86]

water

C/H/O/N/S/Mg/P/Na/Cu/Cl/X

reaxff-zhang2018.ff

CHON2017_weak.ff

Zhang and Van Duin[87]

water

C/H/O/N/S/Mg/P/Na/Ti/Cl/F

reaxff-huygh2014.ff

CHONSMgPNaTiClF.ff

Huygh et al.[88]

water

C/H/O/N/S/Mg/P/Na/Ti/Cl/F

reaxff-kim2013a.ff

TiOCHNCl.ff

Kim et al.[89]

water

C/H/O/N/S/Mg/P/Na/Ti/Cl/F

reaxff-kim2013b.ff

TiClOH.ff

Kim and van Duin[90]

water

C/H/O/N/S/Mg/P/Na/Ti/Cl/F/Au

reaxff-monti2016.ff

CHONSMgPNaTiClFAu.ff

Monti et al.[91]

water

C/H/O/N/S/Mg/P/Na/Ti/Cl/F/K/Li

reaxff-ganeshan2020.ff

CHONSMgPNaTiClFKLi.ff

Ganeshan et al.[92]

water

C/H/O/N/Si/Cu/Ag/Zn

reaxff-lloyd2016.ff

AgZnO.ff

Lloyd et al.[93]

water

C/H/O/N/S/Si/Ca/Cs/K/Sr/Na/Mg/Al/Cu

reaxff-psofogiannakis2015.ff

CHONSSiCaCsKSrNaMgAlCu.ff

Psofogiannakis et al.[94]

water

C/H/O/N/S/Si/Na/Al

reaxff-bai2012.ff

CHONSSiNaAl.ff

Bai et al.[95]

water

C/H/O/S/Mo/Ni/Li/B/F/P/N

reaxff-liu2021.ff

CHOSMoNiLiBFPN-2.ff

Liu et al.[96]

water

C/H/O/Si/Na

reaxff-hahn2018.ff

CHOSiNa.ff

Hahn et al.[97]

water

C/H/O/Zn

reaxff-han2010.ff

CHOZn.ff

Han et al.[98]

water

H/O/Si/Al/Li

reaxff-narayanan2011.ff

SiOAlLi.ff

Narayanan et al.[99]

water

H/O/X

reaxff-zhang2017.ff

Water2017.ff

Zhang and Van Duin[100]

water

Zn/O/H

reaxff-raymand2010.ff

ZnOH.ff

Raymand et al.[101]


6.6. ReaxFF Bibliography