Dihedral style for united force field

LAMMPS LAMMPS General Discussion
1

Hi all, I’m trying to run the lammps simulation using the united atom force fierd (UAFF)
the bond, angle, dihedral coeffcients are as follow:

Bond Coeffs

   1  449.50000    1.53000  # ch2,ch2
   2  449.50000    1.53000  # ch2,ch3

Angle Coeffs

   1   60.00000  112.00000  # ch2,ch2,ch2
   2   60.00000  112.00000  # ch2,ch2,ch3
   3   60.00000  112.00000  # ch3,ch2,ch3

Dihedral Coeffs

   1    3.28700   -4.06000   -0.86700    6.48000    0.00000  # ch2,ch2,ch2,ch2
   2    3.28700   -4.06000   -0.86700    6.48000    0.00000  # ch2,ch2,ch2,ch3
   3    3.28700   -4.06000   -0.86700    6.48000    0.00000  # ch3,ch2,ch2,ch3

to make a “.in” file, I think the bond and angle types are both “harmonic”

in this case, does anybody know what the dihedral type is?

Andrew.

2

How about looking up the publication describing UAFF and looking up the functional forms and comparing them to what LAMMPS has to offer?

If you are planning to do simulations with that force field, you should become familiar with it anyway so that you can later accurately describe in your publication(s) what you chose for settings in your simulation and why.