As we know in RDG maps blue colored disks represent strong attraction, green for vdw interactions, and red for steric repulsions. In multiple RDG iso-surface maps of adsorption study I saw some direct bonds rather than only colored disks. What does this direct bond represents?? In the figure that I provided below, Figure 1 shows direct B-O bond and Figure 2 shows a green plate which means weak bonds are here. But what does this direct B-O bond signifies in RDG analysis? By going through a number of literature, I didn't find any clear explanation about this direct bonding??
can anyone please provide me with some insights into this??