These MEAM parameters for elements C and H as well as the diatomic CH are appropriate for energy minimization and reactive molecular dynamics simulations of SATURATED hydrocarbons, where all carbon atoms have the sp3 hybridization (single C-C bonds).^[1] At the current state, MEAM cannot handle unsaturated compounds with great accuracy. Furthermore, these C and H parameters are not appropriate for diamond and graphite systems. Modification of the MEAM potential to include unsaturated C-C bonds, i.e., double and triple bonds, as well as its parameterization for elements oxygen and nitrogen is ongoing work.

For the first time, MEAM can be used to simulate hydrocarbons and hydrocarbon/metal systems, since it has a large parameter database for major metals in the periodic table of elements. Since MEAM is a reactive potential, it can also be used to simulate fracture and fatigue in hydrocarbon-based polymers, such as polyethylene and polypropylene and their composites with nanometals as well as polymer/metal interfaces.

MEAM can be run in both DYNAMO and LAMMPS software packages. The C, H, and CH parameters are given below for both DYNAMO and LAMMPS and give equivalent results.

NOTE: When using the parameters and codes in this website, please cite the paper references at the bottom of this page in your publications.

The C/H potentials are also given at the NIST website of interatomic potentials repository: Hydrocarbons (CH)

MEAM parameters for LAMMPS:

The following two parameter sets should be copied and pasted into two separate text files named library.meam and CH.meam, respectively, in your working directory.

# LAMMPS library.meam file containing MEAM C and H parameters for saturated
# hydrocarbons developed by Sasan Nouranian.
# Reference: Physical Chemistry Chemical Physics, 16(13) (2014):6233-6249.
# This file is used together with the CH.meam file.

# elt        lat     z       ielement     atwt 
# alpha      b0      b1      b2           b3    alat    esub    asub 
# t0         t1              t2           t3            rozero  ibar 

'C' 'dia' 4 6 12.011100 
3.600000 4.200000 4.500000 4.300000 4.180000 3.325000 7.370000 0.640000 
1.000000 0.500000 0.450000 -3.800000 1.000000 -5.000000 
'H' 'dim' 1 1 1.007900 
2.038800 2.720000 2.045000 2.250000 3.000000 0.740000 2.363000 2.500000 
1.000000 0.200000 -0.400000 0.000001 1.500000 -5.000000

# LAMMPS CH.meam file containing the MEAM CH parameters for saturated
# hydrocarbons developed by Sasan Nouranian.
# Reference: Physical Chemistry Chemical Physics, 16(13) (2014):6233-6249.
# This file is used together with the library.meam file.

rc = 3.000000 
delta(1,2) = 2.120000
re(1,2) = 1.020000
delr = 0.1
alpha(1,2) = 3.200000
lattce(1,2) = dim
rho0(1) = 1.000000
rho0(2) = 1.800000
ialloy = 1
emb_lin_neg = 1
bkgd_dyn = 1
erose_form = 0
zbl(1,1) = -100
zbl(1,2) = -100
zbl(2,2) = -100
augt1 = 0
attrac(1,1) = 0.000000 
repuls(1,1) = 0.000000 
attrac(1,2) = 0.050000 
repuls(1,2) = 0.050000 
attrac(2,2) = 0.000000 
repuls(2,2) = 0.050000 
Cmin(1,1,1) = 2.000000 
Cmax(1,1,1) = 2.800000 
Cmin(1,1,2) = 2.000000 
Cmax(1,1,2) = 2.800000 
Cmin(1,2,1) = 0.445000 
Cmax(1,2,1) = 2.800000 
Cmin(1,2,2) = 1.500000 
Cmax(1,2,2) = 2.000000 
Cmin(2,2,1) = 0.520000 
Cmax(2,2,1) = 2.200000 
Cmin(2,2,2) = 0.750000 
Cmax(2,2,2) = 2.800000

MEAM parameters for DYNAMO:

The following two parameter sets should be copied and pasted into two separate text files named meamf and meafile, respectively, in your working directory.

meam data from vax files fcc,bcc,dia    11/4/92 new bcc 12/28/95 
 elt        lat     z       ielement     atwt 
 alpha      b0      b1      b2           b3    alat    esub    asub 
 t0         t1              t2           t3            rozero  ibar 
'C' 'dia' 4 6 12.011100 
3.600000 4.200000 4.500000 4.300000 4.180000 3.325000 7.370000 0.640000 
1.000000 0.500000 0.450000 -3.800000 1.000000 0 
'H' 'dim' 1 1 1.007900 
2.038800 2.720000 2.045000 2.250000 3.000000 0.740000 2.363000 2.500000 
1.000000 0.200000 -0.400000 0.000000 1.500000 0 

 $meacard 
    ntypes=2 
    bsubs(1)=0.000000 
    bsubs(2)=0.000000 
    enames(1)='C','H' 
    kodes(1)='library','library' 
    rcut=3.000000 
    deltas(1,2)=2.120000 
    res(1,2)=1.020000 
    alphas(1,2)=3.200000 
    all(1,2)='dim' 
    legend=0.600000 
    rozros=1.000000,1.800000 
    ialloy=1 
    nn=.f. 
    attrac(1,1)=0.000000 
    repuls(1,1)=0.000000 
    attrac(1,2)=0.050000 
    repuls(1,2)=0.050000 
    attrac(2,2)=0.000000 
    repuls(2,2)=0.050000 
    cmin(1,1,1)=2.000000,cmax(1,1,1)=2.800000 
    cmin(1,1,2)=0.445000,cmax(1,1,2)=2.800000 
    cmin(1,2,1)=2.000000,cmax(1,2,1)=2.800000 
    cmin(1,2,2)=1.500000,cmax(1,2,2)=2.000000 
    cmin(2,1,2)=0.520000,cmax(2,1,2)=2.200000 
    cmin(2,2,2)=0.750000,cmax(2,2,2)=2.800000 
 &end

Examples:

Examples of the use of the C/H parameters to perform simulations in both DYNAMO and LAMMPS software packages are given in the following links:

• Examples in DYNAMO
• Examples in LAMMPS

References

1. ↑ S Nouranian, MA Tschopp, SR Gwaltney, MI Baskes, and MF Horstemeyer, An Interatomic Potential for Saturated Hydrocarbons Based on the Modified Embedded-Atom Method, Physical Chemistry Chemical Physics 16 (13) (2014):6233-6249.