Man, I'm feeling stronger about LK-99 being it. This paper is theoretical and she finds that particular Cu substitutions onto specific Pb atomic sites are key to enabling a band structure that is usually linked to high Tc superconductors.
What this means for the more practical minded is that the synthesis of superconducting LK-99 is not trivial and you need to make the appropriate substitutional alloy for this to work.
This is a DFT paper, and a band structure that is usually seen in high Tc superconductors just naturally came out. She also talks about the strong electron-phonon coupling that naturally arose from the structure, which is always necessary for superconductivity.
I am, by far, the most excited I've ever been about this being a RT, ambient pressure superconductor.
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.
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 large. 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.
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.
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.
Disclaimer: this is not my area of expertise in the slightest.
If we have the ability to computationally determine these things without any experimental data needed, and we know we're looking for a specific band structure, wouldn't we just do an automated search of possible chemistries to find everything producing said band structure?
Then just whittle down that list to the easiest to produce and most common materials for the first to test... what am I missing?
The parameter space for such a search even with a limited number candidate materials is immense. You'd need to guide the search somehow, that band structure might be the one, or it may not be... and every candidate that you flag will have to be synthesized which may not be all that easy.
>> If we have the ability to computationally determine these things without any experimental data needed, and we know we're looking for a specific band structure, wouldn't we just do an automated search of possible chemistries to find everything producing said band structure?
Isn't this a plot point in that one Star Trek movie (episode?) where they go back in time and program a current-day computer to do this?
Does anyone know if there's a way to ensure those "particular Cu substitutions" happen at the correct atomic sites? Or I guess what's the way forward in terms of synthesizing
I’m not an expert in anyway but when I see detailed chemical compositions in an arxiv summary, a patents, and multiple publications, it’s almost like it’s ready to smile at all the scrutiny.
It doesn't reproduce: https://arxiv.org/abs/2307.16802. That doesn't mean there's not something to further investigate, but LK-99, at least as described in the paper, is not it.
It doesn't reproduce in that case, which is a useful data point but may not be the final word. The article linked in this thread suggests why making it may not be all that easy.
Even if LK99 isn't the real deal, god has it been an exciting 2 weeks. Though I know absolutely nothing about material science, I have enjoyed the sheer enthusiasm and optimism the scientific community has shown. I feel like I'm part of something unique and special, something which could have only been achieved by the medium of accessible mass communication. The excitement here is palpable. I feel fortunate to be part of this infinitesimally miniscule portion of human history where I can share this moment with so many people.
I was many times sad to not be in the future just to get more history to read and more ahead on the tech tree as you say. One of the most interesting things in life is the "story" of life itself. I don't mind not living later but I'd really like to know what happens!
This paper is by someone from Lawrence Berkeley National Laboratory, who has run some simulations of LK99 and found features that are associated with high temperature superconductors.
In the last paragraph before acknowledgements, they point to a feature that could make synthesis difficult, then conclude with "Nevertheless, I expect the identification of this
new material class to spur on further investigations of
doped apatite minerals given these tantalizing theoretical
signatures and experimental reports of possible high-TC
superconductivity."
(I'm a high school dropout, worked for a physics project once)
"However, substitution on the other Pb(2) does
not appear to have such sought-after properties, despite
being the lower-energy substitution site. This result hints
to the synthesis challenge in obtaining Cu substituted on
the appropriate site for obtaining a bulk superconducting
sample"
OK I'm starting to actually believe that LK-99 might be the real deal.
It’s sort of an amazing time. All the things we projected were 30 years out 40 years later and manifesting. The degree of skepticism is high, as should be, but the things we knew were achievable just hard to discover are rapidly unfolding. What falls next?
(N.b., I know I’m displaying unreasonable hubris and it’s still more likely than not an illusion or fabrication, but it certainly feels a lot of long term investments are rapidly coming to a head - AI, space, cancer treatments, aging research, EV, even flying cars and fusion - what a great time to be alive)
I’m currently in a Twitter space with some accounts who know more about this process and this question was answered a few minutes ago. To summarize: no one has yet found a way to “steer” which sites get Cu and which ones don’t. This paper simultaneously makes LK-99 look like the real deal but also points out there may be more, or much more work, to reliably direct the replacement. Someone in the space said “if you find a way to get the Cu to the right site that’s a Nobel Prize”
I'm not an expert on chemistry but it sounds like this would make it ridiculously hard to obtain a high quality sample. Copper can substitute for either lead site; I'm not aware of macroscopic processes that would favor one over the other. Problems like that are usually handled ad hoc. The authors seem to have bumped and shuffled their way there through the darkness.
For context, the preparation of tetrataenite was pursued for decades (first partial success October 2022) even though the structure was well-known and the constituents are just nickel and iron.
Out of curiosity, since this seems like a real inflection point toward trending in that direction, if it becomes increasingly likely that LK-99 or similar material is indeed a high-TC superconductor, what will savvy people be positioning themselves to do? What are good investments? What companies will be started, or what will existing companies be pivoting toward?
Open-ended research grants to anyone with moderate training in experimental science to just throw shit against the wall and try every last possible combination of something, without concern for 'publish or perish' or jockeying for status in academia. Lets get our smartest and most dedicated technical people back in labs rather than off making CRUD apps for 10x academic wages.
If this discovery is true, we just got lucky. Based on the story we know of LK-99 it almost didn't happen, and our current system is not set up to make these kinds of discoveries quickly. Throwing billions at 'just go find stuff that matters' basic research is ultra cheap in comparison to humanity not having a high-tc superconductor.
This has been argued by David Deutsch for a long time and I'm glad to see it being replicated here. People should be free to pursue problems that interest them without fear of not returning results that are not deemed "favourable" to the institution. This will help speed up the creation of new "good explanations" which leads to new knowledge.
* Green energy suddenly becomes way more viable. Megaprojects in the most efficient sites can send energy long-distance and store it with effectively no loss, somewhat mitigating regional variations (especially if we have a high-trust world order where a united global grid is viable). (I read LK99 might have some limitations carrying lots of current but presumably other approaches would do better)
* EVs: improved performance of motors, batteries, charge time, and weight - huge shift for the market. Much safer than most current car batteries too.
* Big breakthrough for computing in the form of fast, cool, and efficient zero-resistance transistors. Step change for cutting-edge component performance, all the cloud hyperscalers would completely revamp their compute. TSMC / ASML probably get huge volumes of new orders.
Obviously the first bet is following the patents. Otherwise, my play would be the industrial companies that build things that build things, like factory automation companies, followed by companies that would see a surge in demand from products incorporating room-temp superconductor technology, like TSMC, ASML (maybe Apple/AWS).
Transmission losses aren't really a big problem for the grid. Cost, geopolitics, and resiliency matters more. I don't expect superconductors to change much here.
It's going to be a long time before it's put into use if this paper is correct. While it's exciting that a mechanism has been discovered (possibly), it seems to imply that the current method of synthesizing it is partially luck-based, and not very high quality. Of course, if we do understand how it works, lots of people will put lots of research into making a more reliable process, but it's going to take time. I'm not sure a clear path forward exists.
If it’s shown it’s theoretically possible there’s going to be a gigantic reallocation of resources into productising it and figuring out to make production work. “It’s theoretically possible but hard” is a world of difference away from “unsure if theoretically possible”
I think this is generally true, but also if this is verified it will suddenly have billions of dollars thrown into it overnight... possibly similar to the speed that covid vaccine research was done; there's a TON of money to be made for the first company that can put this discovery to use. This is a once in a lifetime sort of discovery.
That's not that important. What is important is that if it is true that this is the first member of a new class of superconductors, a whole new family if you will and that once the principles are better understood materials scientists can go about their search in a smaller parameter space of which they have proof that at least one set yields results.
Compared to the steps that have been happening in the last decades this one would be absolutely incredible in terms of temperature range, if I understood it correctly they aren't even sure about the upper limit due to a restriction in their measuring gear.
Even if it is, we can coat it in epoxy and deal with it. And even if we can't, remember the first semi-conductor was germanium. If we have a theoretical and practical reproducible RT Superconductor we will very fast find new, better ones.
1) This is simulation result using density functional theory. While a standard method for understanding the electronic structure of materials it often does not do so accurately when correlations (electronic interactions) are strong. In this kind of context (where strong interactions are expected to be necessary to give something like high temperature superconductivity) what one is looking for from a DFT simulation is an indication of what kind of starting point to extend further and include interactions.
2) What is seen here are features called "flat bands". Essentially, the kinetic energy of the electrons relevant at low energies is only weakly dependent on the (crystal) momentum of the particle. Having lots of different states (different momenta) at similar energy usually means the interactions are more important than in materials where the kinetic energy is larger and more dispersive (depends more strongly on momentum). Here the partially filled d-shells of the Cu atoms appear to make a flat band at low energy. This flat band is partially filled and thus is potentially susceptible to interaction induced instabilities.
3) Flat bands can come from trivial features of a crystal as well. If you've got isolated atoms far apart enough that their atomic orbitals barely overlap their bands will be flat. Some of this may be at play here since the Cu atoms seem to be quite distant (7-9 Angstroms or so).
4) Flat bands appear in many many kinds of systems (at the level of DFT, even at the level of experiments, etc, etc) and do not necessarily imply superconductivity, let alone high temperature superconductivity. Even if the presence of flat bands is pointing towards stronger and more important interaction effects these interaction effects can stabilize other kinds of order instead (magnetism, charge order, etc).
5) Predicting what instability is realized is hard and can be quite delicate. There are materials where this can be debated (theoretically and sometimes experimentally) for years. Predicting the onset temperature of the order that is produced is hard. I.e. Don't necessarily expect a reliable estimate of the critical temperature from theory.
> and do not necessarily imply superconductivity, let alone high temperature superconductivity
That's true, but are there superconductors that do not have those flat bands?
If not then it wouldn't be evidence that it is superconducting but it would at least check one more expected property (based on the evidence obtained about superconductors so far).
> That's true, but are there superconductors that do not have those flat bands?
Yes, many. Most (all?) conventional superconductors. High-Tc iron arsenide superconductors discovered ~15 years ago. DFT (without including Hubbard "U" type corrections) for the cuprate high-Tc superconductors also doesn't indicate show flat bands.
Examples that do have flat bands (or similar physics) include the recently discovered twisted bilayer graphene (still very much actively studied), as well as (morally speaking at least) heavy-fermion superconductors (too many to list).
Superconductivity is a phase of matter than can arise in a variety of different ways depending on the details of the underlying physics. So at least when talking about the microscopic mechanism that stabilizes the superconducting state there isn't any single theory or one set of predictions/properties.
There's a lot of optimism in this thread, but does DFT (or any theoretical model really) actually have much predictive value in quantum chemistry? I've always gotten the impression that in this field the proof is in the pudding.
There are so many bad DFT papers out there because it's cheap to do DFT compared to growing and measuring samples carefully. DFT is notoriously unreliable as a predictive tool in strongly correlated systems, though when electron correlations are small it works well. I mean, I want this to be true, but I put little stock in DFT that doesn't calculate observables. So yes, you're right.
The prof who taught us computational chemistry during masters basically said 90% of published results cannot be trusted and most people in this field don't really know what they're doing. Results can look seemingly good and stil be way off from reality, even for very simple molecules. This is a crystal lattice. I take dft and other computational results with a big grain of salt.
GGA-DFT (+ some corrections) used here seems quite ok to me for this system. For more trust into this, I would like similar calculations with other methods to see how similar or different they are. LDA-DFT will most likely not be great (as in most cases), but I would be very interested in some DFT+GW calculations, even though LK99 might not be it's strength.
But it isn't used for its predictive value here, it is used to verify that which is already known (or at least, strongly suggested to be known). That's different than coming up with a compound based on some hunch, this is modeling a compound with a known structure to check that for properties consistent with the expectations.
That's radically different from searching for a compound with particular properties, that is a much more error prone process.
Explaining why is valuable. The band gap described in this paper is common to other high temperature superconductors. While I remain skeptical, this gives a glimmer of hope, and if the material is indeed superconducting, analysis like this is useful in further understanding high temperature superconductors. If it's not superconducting, then this research may yet be interesting -- if the analysis is correct, it would be interesting to know what's different.
It's funny to read all those grammatical mistakes in the abstract. They are probably just not native English speakers, but to me it sounds like they were frantically typing the paper as soon as they finally got results after a 20 hour lab marathon and way too much caffeine. :D
It isn't the prettiest prose i have ever read, but no obvious outright mistakes stick out to me. It doesn't read any worse than the average hn comment.
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What this means for the more practical minded is that the synthesis of superconducting LK-99 is not trivial and you need to make the appropriate substitutional alloy for this to work.
This is a DFT paper, and a band structure that is usually seen in high Tc superconductors just naturally came out. She also talks about the strong electron-phonon coupling that naturally arose from the structure, which is always necessary for superconductivity.
I am, by far, the most excited I've ever been about this being a RT, ambient pressure superconductor.
It seems to my own naive self that if LK99 is the real deal, we mostly just got lucky finding it.
1. Computation cost is large. 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.
Once you know the atomic positions you can then do little perturbation simulations to model phonon dispersions or ask electron density questions.
People vastly over-estimate what we can simulate at any level of fidelity with any scale below purpose-built stuff running on supercomputers..
Is the solid state theory space similarly underdefined that you can find a theory for every result? Or is this paper significant?
If we have the ability to computationally determine these things without any experimental data needed, and we know we're looking for a specific band structure, wouldn't we just do an automated search of possible chemistries to find everything producing said band structure?
Then just whittle down that list to the easiest to produce and most common materials for the first to test... what am I missing?
Isn't this a plot point in that one Star Trek movie (episode?) where they go back in time and program a current-day computer to do this?
edit: OK, I misremembered. Was thinking of this: https://www.youtube.com/watch?v=LkqiDu1BQXY
Then I remember I'm further along the tech tree than they were, and what a gift that is. It's very exciting to watch it update in real time.
Now I'm envious of future generations (I think humanity has a bright future despite the current gloom groupthink).
Deleted Comment
In the last paragraph before acknowledgements, they point to a feature that could make synthesis difficult, then conclude with "Nevertheless, I expect the identification of this new material class to spur on further investigations of doped apatite minerals given these tantalizing theoretical signatures and experimental reports of possible high-TC superconductivity."
(I'm a high school dropout, worked for a physics project once)
OK I'm starting to actually believe that LK-99 might be the real deal.
(N.b., I know I’m displaying unreasonable hubris and it’s still more likely than not an illusion or fabrication, but it certainly feels a lot of long term investments are rapidly coming to a head - AI, space, cancer treatments, aging research, EV, even flying cars and fusion - what a great time to be alive)
Is there a way to force the Cu to the correct site? Or is looking for a new material with similar properties the way forward
For context, the preparation of tetrataenite was pursued for decades (first partial success October 2022) even though the structure was well-known and the constituents are just nickel and iron.
Open-ended research grants to anyone with moderate training in experimental science to just throw shit against the wall and try every last possible combination of something, without concern for 'publish or perish' or jockeying for status in academia. Lets get our smartest and most dedicated technical people back in labs rather than off making CRUD apps for 10x academic wages.
If this discovery is true, we just got lucky. Based on the story we know of LK-99 it almost didn't happen, and our current system is not set up to make these kinds of discoveries quickly. Throwing billions at 'just go find stuff that matters' basic research is ultra cheap in comparison to humanity not having a high-tc superconductor.
* Green energy suddenly becomes way more viable. Megaprojects in the most efficient sites can send energy long-distance and store it with effectively no loss, somewhat mitigating regional variations (especially if we have a high-trust world order where a united global grid is viable). (I read LK99 might have some limitations carrying lots of current but presumably other approaches would do better)
* EVs: improved performance of motors, batteries, charge time, and weight - huge shift for the market. Much safer than most current car batteries too.
* Big breakthrough for computing in the form of fast, cool, and efficient zero-resistance transistors. Step change for cutting-edge component performance, all the cloud hyperscalers would completely revamp their compute. TSMC / ASML probably get huge volumes of new orders.
Obviously the first bet is following the patents. Otherwise, my play would be the industrial companies that build things that build things, like factory automation companies, followed by companies that would see a surge in demand from products incorporating room-temp superconductor technology, like TSMC, ASML (maybe Apple/AWS).
If it’s brittle as f, then it limits its applications for example.
Compared to the steps that have been happening in the last decades this one would be absolutely incredible in terms of temperature range, if I understood it correctly they aren't even sure about the upper limit due to a restriction in their measuring gear.
Deleted Comment
Deleted Comment
1) This is simulation result using density functional theory. While a standard method for understanding the electronic structure of materials it often does not do so accurately when correlations (electronic interactions) are strong. In this kind of context (where strong interactions are expected to be necessary to give something like high temperature superconductivity) what one is looking for from a DFT simulation is an indication of what kind of starting point to extend further and include interactions.
2) What is seen here are features called "flat bands". Essentially, the kinetic energy of the electrons relevant at low energies is only weakly dependent on the (crystal) momentum of the particle. Having lots of different states (different momenta) at similar energy usually means the interactions are more important than in materials where the kinetic energy is larger and more dispersive (depends more strongly on momentum). Here the partially filled d-shells of the Cu atoms appear to make a flat band at low energy. This flat band is partially filled and thus is potentially susceptible to interaction induced instabilities.
3) Flat bands can come from trivial features of a crystal as well. If you've got isolated atoms far apart enough that their atomic orbitals barely overlap their bands will be flat. Some of this may be at play here since the Cu atoms seem to be quite distant (7-9 Angstroms or so).
4) Flat bands appear in many many kinds of systems (at the level of DFT, even at the level of experiments, etc, etc) and do not necessarily imply superconductivity, let alone high temperature superconductivity. Even if the presence of flat bands is pointing towards stronger and more important interaction effects these interaction effects can stabilize other kinds of order instead (magnetism, charge order, etc).
5) Predicting what instability is realized is hard and can be quite delicate. There are materials where this can be debated (theoretically and sometimes experimentally) for years. Predicting the onset temperature of the order that is produced is hard. I.e. Don't necessarily expect a reliable estimate of the critical temperature from theory.
That's true, but are there superconductors that do not have those flat bands?
If not then it wouldn't be evidence that it is superconducting but it would at least check one more expected property (based on the evidence obtained about superconductors so far).
Yes, many. Most (all?) conventional superconductors. High-Tc iron arsenide superconductors discovered ~15 years ago. DFT (without including Hubbard "U" type corrections) for the cuprate high-Tc superconductors also doesn't indicate show flat bands.
Examples that do have flat bands (or similar physics) include the recently discovered twisted bilayer graphene (still very much actively studied), as well as (morally speaking at least) heavy-fermion superconductors (too many to list).
Superconductivity is a phase of matter than can arise in a variety of different ways depending on the details of the underlying physics. So at least when talking about the microscopic mechanism that stabilizes the superconducting state there isn't any single theory or one set of predictions/properties.
That's radically different from searching for a compound with particular properties, that is a much more error prone process.
https://en.wikipedia.org/wiki/Sin%C3%A9ad_Griffin