I have a bunch of geometry optimisations I want to run for a cation Metal-organic complex. This is going to be a repeat of calculations that were done in "Turbomole" previously and my Prof. wants to know, if the same methodology run in Gaussian will return the same results. I also need the same workflow for another project I am working on, so it's not just treading old ground.
Anyways, here's the problem: I've been out of the loop with quantum chemistry for quite a while now and I do not know how I am supposed to create an input file for Gaussian 16 in which two different theory levels are used for different atoms. The metal of the cationic complex is supposed to be treated with a higher theory level than the organic linker and there are some parts of the description that just straight up confuse me...
This is the file I came up with till this point after googling a bunch:
%mem=2GB %chk=checkpoint.chk %nproc=4 #P ONIOM(B3LYP/aug-cc-pVDZ,B3LYP/aug-cc-pVDZ-PP) Opt (4,5-Dichloro-1H-imidazol-1-yl)zinc(II) 1 1 Zn -2.257981 1.679840 0.081127 H N -0.830168 0.416312 0.021160 L C 0.476998 0.704393 0.028443 L Cl 1.236824 2.280002 0.093278 L C 1.162496 -0.516566 -0.026780 L Cl 2.910383 -0.699600 -0.041468 L N 0.218700 -1.486345 -0.064823 L C -1.010691 -0.893184 -0.034491 L H -1.906562 -1.484851 -0.056446 L
I am almost certain this is wrong. I always thought ONIOM was just for QM/MM stuff.
Another thing that confuses me is that the theory level of the zinc ion is supposed to include "Stuttgart-Dresden ECPs"?
How do I fix this? Did I miss that section in the Gaussian reference manual? Is the full manual not available for free online?
As requested, this is the DOI of the paper in question: https://pubs.acs.org/doi/pdf/10.1021/jacs.3c01933
The relevant figure for the QM calculations is Figure 7. The procedure is described in the supporting information under section 2.
The excerpt describing the settings is as follows:
Binding energies haven been computed on the hybrid DFT level or theory with the B3LYP functional and aug-cc-pVDZ basis sets (aug-cc-pVDZ-PP and Stuttgart-Dresden ECPs für Zn) including the dispersion correction D3 with Becke-Johnson damping. The TURBOMOLE (V7.3) suite of programs has been used. We used the resolution of identity (RI) approximation with default auxiliary basis functions and a refined grid “m5” for numerically integrating exchange and correlation contributions. Both the structure of the anionic linker and the cationic product have been fully optimized within Cs symmetry. For linkers with two chemically different nitrogen donors (i.e. two different [Zn(Xim)]+ isomers) both binding energies were computed and averaged. As a descriptor we use the relative binding energy with the basic imidazolate as reference point.