How do I model non-covalent interactions in Gaussian? I'm doing some research about the dyes found in photography, and found Organic Chemistry of Photography
by Shinsaku Fujita, which shows the dyes used. I'm looking at doing an excited states and UV-VIS calculation, of course optimized before with a geometry optimization, with some of the dyes presented in the book. Right now, I'm trying to build number one in the image below, but have come upon a bit of a stumbling block.



The problem is the $\ce{(CH2)3SO2O-}$ and $\ce{(C2H5)3NH+}$ part on the rightmost nitrogen, as I'm not sure how to model the interaction between $\ce{(CH2)3SO2O-}$ and  $\ce{(C2H5)3NH+}$ (triethylamine), as both have no more covalent bonds available.

To visualize the problem, I built out two molecules (everything but triethylamine as one, then triethylamine below). As you can see, both are connected with as many covalent bonds as possible.




How can I model the interaction between the two molecules (pictured above) in Gaussian, for UV/Vis calculations?
As hBy2Py, Greg, and others have pointed out in their comments, the cation is just a counter ion for your benzothiazole-based cyanine dyes.

I suggest to be reasonably lazy and perform the calculations on the cyanine dye only. 

Even for calculations in solvents of sufficient polarity (from an experimental photochemical perspective, acetonitrile seems to be a good choice), I would just ignore the cations.