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Re:Origin of correlated isolated flat bands in LK99 by bibabaloo on Tuesday August 01, 2023 @12:35AM (#36952350)
If this could be simulated, can you help me understand why we couldn't have used simulation to find promising SC materials to investigate further earlier? Are there just too many permutations to investigate?

It seems to my own naive self that if LK99 is the real deal, we mostly just got lucky finding it.

Re:Origin of correlated isolated flat bands in LK99 by ivalm on Tuesday August 01, 2023 @12:44AM (#36952424)
You have to put in the structure and then it's expensive to do the calculation. The space of possible structures is extremely large. If you have candidates then you can run through them, but you can't just random search through trillions of trillions of candidates.
Re:Origin of correlated isolated flat bands in LK99 by KRAKRISMOTT on Tuesday August 01, 2023 @12:58AM (#36952497)
What are all the material science ML companies doing? This would be a perfect technology demo if they can find the target
Re:Origin of correlated isolated flat bands in LK99 by throwawaymaths on Tuesday August 01, 2023 @01:28AM (#36952676)
The problem is that this stuff is severely nonlinear, and for the raw formula there are not that many degrees of freedom to try. If you get a structure, there is no guarantee it's stable, or accessible by our synthetic techniques.

Obtaining the training data is also likely to be tricky.

Re:Origin of correlated isolated flat bands in LK99 by jacquesm on Tuesday August 01, 2023 @01:04AM (#36952524)
https://www.mpg.de/20096180/artificial-intelligence-in-mater...

They are doing this sort of thing (that's more of a research institute). The problem is that you are not looking for the compound but for the exact way to manufacture it assuming that the original sample really is superconducting.

Re:Origin of correlated isolated flat bands in LK99 by Hermitian909 on Tuesday August 01, 2023 @02:14AM (#36952902)
I've worked on the CS side of new material discovery.

The tricky thing is that you don't actually have that much data so ML is not even close to plug and play. If you want to get results you end up needing to pair ML with a lot of theory and some tricky algorithms to help narrow the search space and even then that space is huge.

Progress is being made but I think we're still at least 5-10 years from CS providing a real inflection in materials discovery.

Re:Origin of correlated isolated flat bands in LK99 by doingtheiroming on Tuesday August 01, 2023 @02:30AM (#36953007)
The positive view here is that we are 5-10 years from being able to search for materials computationally using AI. That would potentially be more valuable than a single RTS.
Re:Origin of correlated isolated flat bands in LK99 by m463 on Tuesday August 01, 2023 @12:52AM (#36952472)
yet.
Re:Origin of correlated isolated flat bands in LK99 by jacquesm on Tuesday August 01, 2023 @12:54AM (#36952479)
And then you have to synthesize your candidates to ensure that what you think will happen really happens.
Re:Origin of correlated isolated flat bands in LK99 by tired_and_awake on Tuesday August 01, 2023 @12:46AM (#36952429)
DFT scales horribly so it's phenomenally expensive to run. You have to have some other mechanism for knowing the general atomic layout before entering the DFT realm.

Once you know the atomic positions you can then do little perturbation simulations to model phonon dispersions or ask electron density questions.

Re:Origin of correlated isolated flat bands in LK99 by rpep on Tuesday August 01, 2023 @03:25AM (#36953337)
There are linear scaling DFT codes but they’re not available under open source licensing, only a strange license:

https://onetep.org/

Re:Origin of correlated isolated flat bands in LK99 by marcosdumay on Tuesday August 01, 2023 @11:19AM (#36957122)
What the fuck?

Linear scaling DFT is something way more impactful than room-temperature superconductors. What's next? "Hey, I've used my FTL spaceship to verify the material at those friendly alien's library"?

The fact that there has been no Nobel prize and we didn't spend a week around the web arguing "yes, it works!", "no, didn't work for me", "yes, I verified it!" highly implies that the site is trying to say something different than what we are understanding.

Re:Origin of correlated isolated flat bands in LK99 by tired_and_awake on Tuesday August 01, 2023 @11:44PM (#36966724)
I'm not intimately familiar with it, just guessing this is some orbital free method that theyve refined. Nothing new, just another approximation that cant model some effects.
Re:Origin of correlated isolated flat bands in LK99 by justinclift on Wednesday August 02, 2023 @04:52AM (#36968586)
Poking around the website, it seems to be owned by Dassault Systems and available for commercial licensing as part of their "Biovia Material Studio" product. PDF flyer about it here:

https://www.3ds.com/fileadmin/PRODUCTS-SERVICES/BIOVIA/PDF/b...

Re:Origin of correlated isolated flat bands in LK99 by akasakahakada on Tuesday August 01, 2023 @01:33AM (#36952699)
Not an expert but it just happen that my lab is full of DFT folks so I heard a lot about those everyweek. As people above already answered the questions, I gonna talk some extras.

1. Computation cost is larger. 1 compute task for a small scale ~100 atoms last about 3 days to 1 week on supercomputer.

2. Search space is hugh. For each composition you can have different atomic (or crystal) structure. And here we are talking doping which means introduce impurities into the molecule. Chemical characteristics differs depending on which atom you swap for the impurity. Sometimes you may want to try all places.

3. Depends on initial values. Sometimes the initial value is just bad that the result is totally unusable, then you have tweak a little bit and throw back to supercomputer. This cycle might happen few times for 1 specific formula and structure.

4. Not 100% accurate. Often the resulting numbers are off by a few % or more which is hugh, compare to experimental results. Reason is that the simulation is not full scale, approximation is here and there to reduce computational cost.

Re:Origin of correlated isolated flat bands in LK99 by fpordeig on Tuesday August 01, 2023 @04:40AM (#36953792)
This looks similar to the protein folding problem. Maybe an AlphaFold-like approach could work?
Re:Origin of correlated isolated flat bands in LK99 by fock on Tuesday August 01, 2023 @05:14AM (#36954011)
not soo similar really, but yes, alphafold-style generative models could help find realistic structures for a specific composition. However a) data is much worse (I would say so at least...), b) the clever tricks of alphafold centered around strings of aminoacid don't really apply to particles in a box... and c) search space might be even larger if you go to interestingly sized systems.

Also there's been some people arguing about the particles in a box situation for a loooong time and the most promising approach currently is diffusion.

Re:Origin of correlated isolated flat bands in LK99 by akasakahakada on Tuesday August 01, 2023 @05:27AM (#36954083)
We exactly considering this since this year. But there are some major problems that cannot be solved in short term.

Inorganic crystal structure database (and there is one database literally is this name) is way smaller than what we have for proteins. Also by nature, Transformer is hardly useful for crystals because the crystal is repetitive. You don't throw the same sequence over and over to transformer and hope it will work like magic.

My current understanding is that Graph Neural Network is perfect for this job because graph can exactly describe this kind of repetitive nature of crystal.

Re:Origin of correlated isolated flat bands in LK99 by rsfern on Tuesday August 01, 2023 @07:50AM (#36954848)
GNNs and graph transformers are the current state of the art methods for this kind of crystal property prediction task. One drawback is that they don’t seem to capture long range structure all that well, and the current generative models (which are really cool) based on GNNs don’t seem to take advantage of symmetry that well
Re:Origin of correlated isolated flat bands in LK99 by ssijak on Tuesday August 01, 2023 @04:50AM (#36953853)
Based on your descriptions, if LK99 is real, it sounds like there are closer to infinite than 0 of these materials. If there are so many combinations and somebody randomly stumbled on one, it makes sense that if the number of combinations is asymptotically infinite, that number of superconducting materials is very large.
Re:Origin of correlated isolated flat bands in LK99 by azalemeth on Tuesday August 01, 2023 @11:48AM (#36957622)
The other thing is that a lot of the results depend entirely on what you put into them. Sounds lovely and obvious, but really isn't. Which basis set would you use for simulating your molecular object of interest? There are hundreds to choose from, all developed for different purposes and under different assumptions (eg "frozen core", Born Oppenheimer, Slater orbitals, etc). It's very much not trivial to know what you need, because what the system does answers that question, and in order to find out what the system does you need to solve it -- for which you need a basis set!

It's hard enough to get out the hyperfine interaction to the right order of magnitude of a simple metal complex, let alone something like superconductivity, which fundamentally is a many, many body problem...

Re:Origin of correlated isolated flat bands in LK99 by Sharlin on Tuesday August 01, 2023 @03:32AM (#36953385)
It's like NP problems. It's much harder to find a solution than to check if a candidate solution is valid.
Re:Origin of correlated isolated flat bands in LK99 by marcosdumay on Tuesday August 01, 2023 @10:57AM (#36956793)
Yes, the permutations are endless, and verifying each one is a bit expensive (up to extremely expensive, depending on the complexity of the material).
Re:Origin of correlated isolated flat bands in LK99 by foobiekr on Tuesday August 01, 2023 @11:40AM (#36957484)
Because it's too hard.

People vastly over-estimate what we can simulate at any level of fidelity with any scale below purpose-built stuff running on supercomputers..

Re:Origin of correlated isolated flat bands in LK99 by currymj on Tuesday August 01, 2023 @04:36PM (#36962411)
cheaper alternatives to DFT (using ML especially) for this purpose is an active research area