Hello Everyone, I am trying to edit LAMMPS data file in PCFF format. While using PCFF for my system. I found PCFF use automatic parameters for some combinations like 

Bond Stretch : (c2 nb) 

While I look LAMMPS data file, I found that for given combination, coefficients are missing

Bond Coeffs # class2

10 0.0000 000.0000 0.0000 0.0000 # c2-nb

so I edited the parameters using auto equivalency method. I did same for Angle Bend, Torsion. But combination for Inversion doesn't match which was not case with Bond stretch, Angle bend, Torsion. 

Why are they different from each other?

MS uses the automatic parameters for combination (nb c2 c2 cp), (nb c2 cp c2), (nb c2 cp hn), (nb cp hn c2), (nb hn c2 cp). But LAMMPS data file shows missing improper coefficients for different combinations that was not case with Bond Stretch, Angle Bend, Torsion. 

Energy contributors using automatic parameters:

Inversion : (nb c2 c2 cp), (nb c2 cp c2), (nb c2 cp hn), (nb cp hn c2), 
: (nb hn c2 cp)

But in LAMMPS

Improper Coeffs # class2

1 7.8153 0.0000 # c2-cp-cp-cp
2 4.8912 0.0000 # cp-cp-cp-hc
3 13.0421 0.0000 # cp-cp-cp-oc
4 7.8153 0.0000 # cp-cp-cp-c3
5 10.7855 0.0000 # cp-cp-cp-nb
6 0.0000 0.0000 # c2-nb-c2-cp
7 0.0000 0.0000 # c2-nb-cp-hn
8 0.0000 0.0000 # cp-nb-hn-hn
9 0.0000 0.0000 
10 0.0000 0.0000 
11 0.0000 0.0000 

...

31 0.0000 0.0000

Thanks,

Ankit