3 ms·
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
by montecarl 3y ago
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 3y agoThe 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 3y agonaive question: if we can simulate this, can't we brute force other superconductors?
- fzzzy 3y agoYes, but the search space is mind boggling.
- chevman 3y agoHow so? Just a function of all the different atoms and sub-atomic particles interacting?
- montecarl 3y agoI'll link to another reply of mine: https://news.ycombinator.com/item?id=36966474 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.
- adw 3y agoNot 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).