I am wondering if I can use dihedral_style = charmm in combination with special_bonds = amber.
Reason I am asking is, any time I am changing the dihedral_style from harmonic to charmm I am getting an error.
I checked the data file and there are indeed no dihedral_coeff of the form 1 120.0 1 60 0.5 present; therefore the error.
The Cornell article describes the dihedral potential closer to the charmm dihedral than the harmonic potential.
Thank you very much in advance for your help,
P.S. The data file has been obtained with AmberTools and converted with the python script provided with Lammps.