[montecarl]

The thing that stands out to me is that the DFT simulations show that the flat bands only occur in a particular crystal structure of the material and it is not the most stable state (at least according to the simulation). This would explain the synthetic challenges involved. These simulations are not perfect, but they can be VERY useful when guided by experiment and when they correlate strongly it is a good sign that you have a mechanistic explanation of the phenomenon.

[adw]

The way I'd characterize it is that they're usually _directionally_ (and mechanistically) correct. On something as sensitive as a band gap the error bars are larger; if the DFT simulations said "yeah, no way this has band density at the Fermi level" I'd regard it as strong evidence against the LK-99 claims, but the fact this is in the ballpark is – to be clear, pretty weak – evidence in favor.

[yreg]

naive question: if we can simulate this, can't we brute force other superconductors?

[adw]

Not really. Think of this as being analogous to public key/private key crypto; it's easy to check a signature (simulate a structure), it's extremely hard to forge one (design a new material ab initio).

[fzzzy]

Yes, but the search space is mind boggling.

[chevman]

How so? Just a function of all the different atoms and sub-atomic particles interacting?

[montecarl]

I'll link to another reply of mine: https://news.ycombinator.com/item?id=36966474

The "just a function of" is a non-trivial problem. Given a single set of elements you want to "try out" results in a huge global optimization problem to find the set of stable structures (low energy). When aided by experimental data it becomes a tractable problem.