Greetings to everyone!
I’m trying to find some information about neighbours list for VdW interactions creating principle in DL_POLY Classic. As far as I know, there are several ways to consider Van der Waals interactions in literature; for example:
- 1-2 case: all atom pairs that are directly connected via a linear bond will be excluded from VdW interactions list;
- 1-3 case: all 1-2 pairs will be excluded along with all pairs of atoms that are bonded to a common third atom (i.e., if atom A is bonded to atom B and atom B is bonded to atom C, then the atom pair A-C would be excluded);
- 1-4 case: all 1-3 pairs will be excluded along with all pairs connected by a set of two bonds (i.e., if atom A is bonded to atom B, and atom B is bonded to atom C, and atom C is bonded to atom D, then the atom pair A-D would be excluded);
- scaled 1-4 case: all 1-3 pairs are excluded and all pairs that match the 1-4 criteria are modified with the scaling factor. For example, this factor is equal to 0.5 in OPLS force field.
The DL_POLY Classic manual says, that the scaling factor can be defined for the scaled 1-4 case, if there is a dihedral angle specified. But what if the structure (and the FIELD file) doesn’t contain any dihedral angles potentials? Which case of considering the VdW interactions and creating of the neighbors list for it is used in DL_POLY Classic?
Any help would be appreciated.