Atomic Partial Charges in Molecules — Towards A Guide For The Perplexed
Jan Martin, Dept. of Organic Chemistry, The Weizmann Institute of Science, Rehovoth
2 PM via Zoom
Click here for the ZOOM presentation
There are dozens of atomic partial charge distribution types (Mulliken, NPA, CHELPG, QTAIM, Hirshfeld,…) in the field, and it’s very easy to get lost in them.
With the help of a talented and hard-working summer student from Brown University, we generated a very large dataset from the 2000+ molecules in the GMTKN55 benchmark, then applied principal component analysis. We found that nearly all the variation in the dataset can be captured with just 2-3 principal components: a “principal component of ionicity”, a second component that pits QTAIM (Bader) against almost everybody else, and a weaker third that put electrostatic against orbital-based charges. For the single charge distribution that most closely resembles the first principal component, it’s a toss-up between Hirshfeld-I (iterative Hirshfeld) and a minimal-basis-set-projected variant of Bickelhaupt.