Corin C. Wagen and Jonathon E. Vandezande (2024)
Highlighted by Jan Jensen
While this is an interesting paper, a cursory reading (like the one I did initially) can leave you with the wrong impression. The paper shows that the vDZP basis set that Grimme and co-workers develops as part of the ωB97X-3c method gives good results with other functionals. The results are always better than using other DZ basis sets and sometimes better using than TZ or even QZ basis sets, depending on the property! That's the good news.
The bad news the computational cost of the vDZP basis set is about 40% more expensive than a TZ basis set (at least for typical organic molecules). The reason is that the vDZP consists of more primitives compared to a typical TZ basis set (but considerably less compared to a typical QZ basis set).
So, for me, the main take-home message is that there is a basis set that is somewhere between TZ and QZ in cost, that may be worth trying if the TZ results are not acceptable but QZ is too expensive. However, the paper doesn't show any convincing examples of this. Yes, for isomerization reactions, B97-D3BJ/vDZP is more accurate than B97-3c (which uses the mTZVP basis set) and even B97-D3BJ/def2-QZVP. But you get much better (and faster) results by using r2SCAN-3c (which uses the mTZVPP basis set).
One exception is if you are working with molecules with a lot of heavy atoms (post C row), then vDZP may be faster than TZ basis sets, because it uses ECPs.
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