The expansion of the full Green's dyadic, G = GI, (B11) gives
The expansions of the frequency derivatives of the Green's function (B10) and Green's dyadic (B11) give
In addition, the full Green's dyadic, G = IG, can be expanded as 
In addition, as far as the Green's dyadic is numerically computed in the source (nanostructures) region, all the electromagnetic properties of the system are easily obtained with practically almost no additional computing cost .
Another notable advantage of this approach is that it considerably reduces the memory cost for evaluating the Green's dyadic. Finally, different mesh shapes can be considered by adapting the integral surface.
[25.] Van Bladel, J., "Some remarks on Green's dyadic
for infinite space," IEEE Transactions on Antennas and Propagation, Vol.