Hi,
in the example located in v9.4.4/examples/setup/chemistry/field/opls/aa, the field selected is opls. EMC works and generates the necessary files. However, in the .params files, the dihedral_style that is selected in LAMMPS is multi/harmonic and not opls. Why is this the default? Is there a way to change this?
EMC converts OPLS-style dihedrals into a multi-harmonic cosine series internally. I am aware of LAMMPS shortcomings, where the expansion of the multi-harmonic only is allowed up to the 5th order. This limitation does not seem to hamper standard OPLS dihedral definitions though.