We are working in this direction. However, analytical expressions for the nuclear gradient (or at least their implementation) get much more complicated in ab-initio methods, when using an atom-in-molecule-adaptive basis set.

Excited states-support is a feature that will also be available with g-xTB in the future (in the final implementation). Stay tuned! :)

You can try it directly here:

github.com/grimme-lab/g...

Happy to receive any feedback, particularly cases where it does not work as expected.

g-xTB excels in areas where SQM and even DFT often struggle:
✅ Transition-metal thermochemistry
✅ Spin-state energies
✅ Orbital energy gaps
✅ Reaction barriers
And all that at a fraction of DFT cost.

g-xTB is built to replace GFN2-xTB in all applications.
It cuts MAEs by half, improves SCF convergence, and even beats B3LYP-D4 for reaction barriers — all with just 30–50% more computational cost than GFN2-xTB.

g-xTB is trained and validated on an extremely diverse molecular set — including actinides and "mindless molecules" (see also: chemrxiv.org/engage/chemr...)
Fully parameterized for Z = 1–103, it’s designed to perform reliably across the entire periodic table.

Some key highlights of g-xTB — our first general-purpose xTB method delivering DFT accuracy at SQM speed.
It tackles not only geometries, frequencies, and NCIs ("GFN"), but also strong thermochemistry and electronic properties with unprecedented accuracy for a semiempirical method.
🔗 #compchem

Two of them are at #WATOC2025 this week and ready to share all the details about the method you’ve been waiting for:
📍 @thfroitzheim.bsky.social — Thursday, Session B1, 9:20 AM
📍 S. Grimme — Thursday, Session A2, 10:20 AM

Don’t miss it!

Big thanks to my amazing co-workers: @thfroitzheim.bsky.social, Stefan Grimme, and Andreas Hansen! 🎉

I see it more as a form of art 😂

I immediately loved the optical appearance of the molecules in this figure when I created it. 😂 But yeah, "unhinged" is very accurate! That's exactly what we wanted. 🤓

Thank you for your question! While an energy expression in the context of density-corrected DFT can still be conceptually very inspiring, we are currently working on a “real” xTB successor, called g-xTB.
This plot about the accuracy of the barrier heights compared to DFT gives a good impression. 💡

Thank you for your question! While an energy expression in the context of density-corrected DFT can still be conceptually very inspiring, we are currently working on a “real” xTB successor, called g-xTB.
This plot about the accuracy of the barrier heights compared to DFT gives a good impression. 💡

This is a question I can only answer with a certain bias, as we are actively developing xTB and related tight-binding methods (which have their roots in DFTB). From this point of view, I would answer “No, xTB has become the standard, at least for molecular systems with less than about 2000 atoms.” 🤓

2. See this answer: bsky.app/profile/mrcl...
Thus, I consider models that have a built-in quantum chemical foundation in them as semiempirical (in the sense of theoretical chemistry/quantum chemistry methods).