Simulation of electronic potential from nanoparticles interacting with molecules

Question

I work with SERS, where the Raman signal gets enhanced by the electric field of the nanoparticles. Now I like to simulate this kind of spectrum with Gaussian. I found a paper[1], where it looks very nice how they simulate it. They don't get a bond between the molecule and the silver nanoparticle. If I try it on my own, then the nanoparticles are thrown away by Gaussian. Has anyone of you an idea of how they simulate it? My idea is the following workflow: Frist, they optimize the attached molecule alone; after this, they made a scan with one variable. The variable is the distance between the part of the molecule where the nanoparticle should attach and the nanoparticle itself. And after this, they put the nanoparticle in the distance with the lowest energy and make a single point calculation with options to get the orbitals and the ESP mapping. It makes sense, or is it not an ordinary workflow for gaussian? I learned Gaussian myself so I'm not sure at all.

[1] Gao, Y.; Xu, M.-L.; Xiong, J. J. Environ. Sci. Heal. Part B 2019, 54, 665-675

Answer 1

I already did the same type of calculation but for different system (functionalized carbon nanotube interacting with heavy metals).

About your workflow, the only step I will do different is that instead a single point optimization I'll run a full geometry optimization. This is due that you can not be sure that the point you selected from the scan correspond, exactly, to the minimum potential energy (even with a dense scan).

Related to the nanoparticle being thrown away, I will play with different methods (semiempirical, DFT, Hartree-Fock), with different functionals and with different basis sets (I am not too sure if B3LYP is a good choice for silver).