In constructing DGLGraphs from molecules by DGL-LifeSci, it seems that ionic bonds are ignored, e.g., the DGLGraph of the molecule with the smiles notation ‘[I-].[K+]’ is defined as a graph with two isolated vertices. Therefore, in some message passing techniques which are based on edge features (such as in the directed message passing, e.g., here), ionic bonds are ignored. But, it seems that by considering such bonds, the property prediction of the molecules might be done more accurately.
Why is such a bond not considered as an edge in the definition of DGLGraphs?
Since ionic bonds are important in the property prediction of a molecule, what is the best approach to consider such bonds in the definition of DGLGraphs or their related message passings?