I’ve noticed that there are several azides in Materials Project which are predicted to be on the convex hull, even though experimentally they decompose explosively. Examples include CaN6 and NaN3, with CaN6 having an experimental decomposition energy of -483 meV/atom (A. D. Yoffe, Proc. Royal Soc. A 208 (1951)) while the calculated value is +478 meV/atom.

- Do you know why the discrepancy is so large? Of course, the experimental decomposition happens around 400-500 K, but that doesn’t seem like it would explain such a large difference. The formation energy for Ca3N2 is almost exactly in agreement with experiment, it’s just the azide which is so far off target.
- Do you have any recommendations for how I could calculate a more accurate value that is still somewhat compatible with MP parameters, in order to draw a more accurate convex hull?

Thank you