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Electronic Structure of LK-99

arxiv.org

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Re: Electronic Structure of LK-99

#31

Post by appplication »

vesinisa wrote: post #26
appplication wrote: post #20

This ongoing research saga pretty much the most excited I’ve been about anything since before Covid. It feels like the science equivalent of watching your favorite sports team on an epic rise towards winning a world championship. Even if this turns out to flop, I hope history remembers the original authors favorably. They really did find something that by all accounts could plausibly be a room temp superconductor. An…

Just curious, how did you find Covid "exciting"? Making lots of money on the bear market?

Perhaps poorly worded, I meant since before. During Covid I lost a lot of zest for life, felt like I went to sleep in my 20s and woke up an old man.

Re: Electronic Structure of LK-99

#32

Post by soligern »

redrobein wrote: post #29
anigbrowl wrote: post #17

Earlier quoted context omitted.

So happy to hear this. I've been hoping for some sort of breakthrough ever since I first encountered footage of magnets falling through Cu tubes at an extremely leisurely pace.

Any conductive material for the tube will have a similar effect. It isn't specific to copper. The moving magnet induces a current in the tube which in turn creates the magnetic field that interacts with the magnet.

Eddy currents

Re: Electronic Structure of LK-99

#33

Post by westurner »

zeronullempty wrote: post #3
itsthecourier wrote: post #2

So theorically they agree with LK-99 reaching superconductivity?

More specifically they agree with another similar paper from Stanford's Sinead Griffin https://arxiv.org/abs/2307.16892

"Origin of correlated isolated flat bands in copper-substituted lead phosphate apatite" (2023) https://arxiv.org/abs/2307.16892 :

> Abstract: A recent report of room temperature superconductivity at ambient pressure in Cu-substituted apatite (`LK99') has invigorated interest in the understanding of what materials and mechanisms can allow for high-temperature superconductivity. Here I perform density functional theory calculations on Cu-substituted lead phosphate apatite, identifying correlated isolated flat bands at the Fermi level, a common signature of high transition temperatures in already established families of superconductors. I elucidate the origins of these isolated bands as arising from a structural distortion induced by the Cu ions and a chiral charge density wave from the Pb lone pairs. These results suggest that a minimal two-band model can encompass much of the low-energy physics in this system. Finally, I discuss the implications of my results on possible superconductivity in Cu-doped apatite

Re: Electronic Structure of LK-99

#34

Post by poopbutt7 »

jeffbee wrote: post #16

The most interesting phenomenon revealed so far is that the room-temperature superconductor people and the generative-LLMs-are-God people draw on the same limited global pool of credulity, such that HN cannot be flooded with both ChatGPT worship and superconductor speculation at the same time.

[flagged]

Re: Electronic Structure of LK-99

#36

Post by dekhn »

rsfern wrote: post #28
dekhn wrote: post #10

Earlier quoted context omitted.

yes, but if you reported 100 different substances reaching superconductivity, 100 theorists will publish papers demonstrating their model supports the observation... regardless of whether those substances actually reach superconductivity. (put another way: it's post-hoc)

Sure it’s post hoc, but these are ab initio calculations, there’s not all that much wiggle room that you could make anything you like come out looking like a superconductor. Plus now I’ve seen three calculations with three different functionals and reasonable convergence criteria and they all find similar electronic structure

Well, then why spend all this time searching in a lab? Instead, run a bunch of simulations until the compounds with properties you desire just sort of pop out as the top hits in your simulations?

(I say this as somebody with a decade+ of experience running large ensembles of classical MD simulations, but not so much experience with inorganic DFT)

Re: Electronic Structure of LK-99

#37

Post by TuringTourist »

vesinisa wrote: post #26
appplication wrote: post #20

This ongoing research saga pretty much the most excited I’ve been about anything since before Covid. It feels like the science equivalent of watching your favorite sports team on an epic rise towards winning a world championship. Even if this turns out to flop, I hope history remembers the original authors favorably. They really did find something that by all accounts could plausibly be a room temp superconductor. An…

Just curious, how did you find Covid "exciting"? Making lots of money on the bear market?

Once in a lifetime events tend to be "Exciting" to people, watching history unfold so to speak. The excitement comes from the awareness of this fact, and the fact that it might never be seen again.

Re: Electronic Structure of LK-99

#38

Post by civilitty »

jeffbee wrote: post #16

The most interesting phenomenon revealed so far is that the room-temperature superconductor people and the generative-LLMs-are-God people draw on the same limited global pool of credulity, such that HN cannot be flooded with both ChatGPT worship and superconductor speculation at the same time.

You're seeing a lull in ChatGPT-specific posts but there are two LLM posts [1][2] on the front page as I write this (compared to three LK99 posts).

There does not seem to be any conservation of credulity going on here.

[1] https://news.ycombinator.com/item?id=36958731

[2] https://news.ycombinator.com/item?id=36958175

Re: Electronic Structure of LK-99

#39

Post by dekhn »

appplication wrote: post #20

This ongoing research saga pretty much the most excited I’ve been about anything since before Covid. It feels like the science equivalent of watching your favorite sports team on an epic rise towards winning a world championship. Even if this turns out to flop, I hope history remembers the original authors favorably. They really did find something that by all accounts could plausibly be a room temp superconductor. An…

Pons & Fleischman was exciting for about 3 days. Some folks kept looking for decades after.

Re: Electronic Structure of LK-99

#40

Post by westurner »

"Electronic structure of the putative room-temperature superconductor [ Pb_9 Cu( PO_4)_6 O ]" (2023) https://arxiv.org/abs/2308.00676 :

> A recent paper [Lee {\em et al.}, J. Korean Cryt. Growth Cryst. Techn. {\bf 33}, 61 (2023)] provides some experimental indications that Pb10−xCux(PO4)6O with x≈1, coined LK-99, might be a room-temperature superconductor at ambient pressure. Our density-functional theory calculations show lattice parameters and a volume contraction with x -- very similar to experiment. The DFT electronic structure shows Cu2+ in a 3d9 configuration with two extremely flat Cu bands crossing the Fermi energy. This puts Pb9Cu(PO4)6O in an ultra-correlated regime and suggests that, without doping, it is a Mott or charge transfer insulator. If doped such an electronic structure might support flat-band superconductivity or an correlation-enhanced electron-phonon mechanism, whereas a diamagnet without superconductivity appears to be rather at odds with our results.

Superconductivity: https://en.wikipedia.org/wiki/Superconductivity

Superconductor classification: https://en.wikipedia.org/wiki/Superconductor_classification

Room-temperature superconductor: https://en.wikipedia.org/wiki/Room-temperature_superconducto...

Diamagnetism: https://en.wikipedia.org/wiki/Diamagnetism

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