This is one of the potential files. This defines parameters relevant to interactions between Iron and Carbon atoms. Copy and paste the text in to a file named FeC.meam

# Fe-C alloy MEAM potential parameters from Phys. Rev. B 89, 094102
# Developed using April 2011 version of LAMMPS (lammps.sandia.gov)
# Should work on recent release of LAMMPS
# Contact information: lsiliyanage@gmail.com (Dr. Laalitha S. I. Liyanage)
augt1=0
ialloy=1
nn2(1,1)=1
nn2(2,2)=1
nn2(1,2)=1
rc=4.500000 
repuls(1,1)=0.300000 
Cmin(1,1,1)=0.680000 
Cmax(1,1,1)=1.900000 
Cmin(2,2,2)=2.000000  
Cmax(2,2,2)=2.800000 
lattce(1,2)='b1' 
repuls(1,2)=0.125301 
attrac(1,2)=0.125301 
delta(1,2)=0.002348 
alpha(1,2)=4.750000 
re(1,2)=1.920000 
rho0(1)=1.000000 
rho0(2)=5.491125 
Cmin(1,1,2)=0.059531 
Cmax(1,1,2)=2.800000 
Cmin(1,2,1)=2.000000 
Cmax(1,2,1)=2.800000 
Cmin(1,2,2)=2.000000 
Cmax(1,2,2)=2.800000 
Cmin(2,2,1)=0.507375 
Cmax(2,2,1)=2.800000