I'm picking up quantum chemistry after a three year break. I've forgot a lot and I'm now using ORCA (version 4.0.1.2).

My system is a non-enzymatic chemical reaction between lysine, arginine (just the functional groups) and D-glucose in a water solvent and no atom heavier than oxygen. So, lots of structure minimisation, geometry scans and transition state searches.

Sadly, after three years my knowledge of the appropriate theory and basis set has now all but gone.

I am using:

- wb97xd-d3 as a long-range GGA hybrid with dispersion and good treatment of van der waals forces.

-def2-TZVP basis set

-CPCM(water) solvent

-Numerical calculation of frequencies, as this version of ORCA can't perform population analysis with CPCM(water).

-TightOpt - earlier optimisation calculation resulted in an imaginary frequency.

My ORCA execution is therefore:

! wB97X-D3 NORI TightOpt NumFreq def2-SVP PAL16 MORead NoFinalGrid Grid4

A big broad question and bearing in mind that it's been quite a few years but, does this come across as appropriate?

Thanks

Anthony