Using PCFF via OpenKIM – #3 by serge – OpenKIM

Hi Serge,
IFF is a bonded force field (bond_style, angle_style, etc.) as opposed to a pair_style type potential, so it is handled in a different manner by KIM. This IFF potential has 75 atom types that are defined in its parameter file ( You need to specify this number (75) in your create_box command. You also need to use the appropriate types (as preset in the file linked above). For example, if your simulation contains atoms of IFF type oy1, they would be referred to as atom type 7 in your LAMMPS script. We are in the process of implementing a more flexible approach that would directly use string labels for atom species (like oy1) in LAMMPS input scripts and data files, but that’s not quite ready yet.

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