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More DFT? Haven't we concluded that has little predictive power?
by carabiner 3y ago
More DFT? Haven't we concluded that has little predictive power?
- chc4 3y agoMore people saying it sounds feasibly like it could be a superconductor is great, but agreed - https://nitter.net/MichaelSFuhrer/status/1686267690770739200 https://nitter.net/MichaelSFuhrer/status/1686267690770739200 and similar threads by actual experts in the field have outlined that DFT studies ignore a lot of variables that need to line up for superconductivity, in harsh contrast to techbros on Twitter claiming they're proof of the next thousand year golden era.
- carabiner 3y agoYeah the techbros have been the worst. Coffee guy went from saying the first DFT paper should deserve a Nobel to, "it's not a strong signal of anything" in 12 hours. WTF. All the actual scientists have been rock steady at, "it is probably not going to replicate," especially CMTC. Techbro speculation on physics should be considered harmful.
- objektif 3y agoCMTC comes of as a whiny little POS tbh. They have the exact opposite of the attitude I would have expected from a scientist. In their first thread regarding this topic they were almost flat out belittling the og authors. WTF.
- selimthegrim 3y agoBecause CMTC has high theory standards and the authors, to put it charitably, didn’t
- objektif 3y agoThis is the one from the all infamous University of Maryland correct? lol.
- selimthegrim 3y agoThey may have been throwing a bit of shade around lately but they are by and large reputable scientists barring whatever SDS’s past MA announcement involvement was. It’s more than just him there.
- objektif 3y agoI do not (almost everyone else too) associate "reputable scientist" with University of Maryland. So they should show a bit of humility.
- selimthegrim 3y agoShow me where on the doll they touched you.
- objektif 3y agoHey no need to get sensitive about it. I am seriously saying University of Maryland (chuckle) is just not enough for bragging rights. Do not worry may he when you grow up you will end up in an ivy.
- selimthegrim 3y agoI don’t have anything to do with them and I went to Caltech.
- selimthegrim 3y ago*MS not MA
- cthalupa 3y ago>All the actual scientists have been rock steady at, "it is probably not going to replicate," especially CMTC. Sinéad Griffin isn't an actual scientist? https://en.wikipedia.org/wiki/Sin%C3%A9ad_Griffin https://en.wikipedia.org/wiki/Sin%C3%A9ad_Griffin Plenty of real scientists are excited by the DFT results while cautioning they are merely supporting evidence and not conclusive evidence.
- xorbax 3y agoIf DFT agrees with reality, it's fine If it produces unphysical nonsense, you can always say "You should have considered xyz!" Computational chemistry inherently cannot consider everything we understand about chemistry or physics or consider beyond certain scales, so its accuracy and precision are limited. You have to constrain the space properly, which makes people a little dismissive.
- Zpalmtree 3y ago> tech bro speculation on physics should be considered harmful why?
- semajian 3y agoThanks for linking someone who knows what he's talking about, very painful to see these DFT papers overhyped as some kind of proof... It proves almost nothing
- rtpg 3y agoWhat does DFT prove beyond the pedantic "it proves what it proves"? Or rather, does it not heavily lean towards some reality?
- tnecniv 3y agoI’d be interested in seeing a source on that. My understanding was that it was a powerful and popular computational tool. The theory is approximate but approximate theories can still be quite useful if the approximation is a good one.
- semajian 3y agoIt's basically an open secret, no one really believes DFT has much predictive power in strongly correlated systems (where relevant electrons cannot be treated as independent). It's not useless, but DFT calculations require many arbitrary choices and are hardly "first principles" in a meaningful way.
- opticfluorine 3y agoThe LBNL DFT paper isn't claiming to have modeled the strong correlations. Rather, they observe a specific feature of the band structure (flat bands crossing the Fermi level formed from d-orbitals) that have also appeared in DFT calculations of other high-temp superconductors and are considered a signature of those materials. In the other high-Tc materials, the calculations are consistent with experiment, and so the unexpected appearance of these bands in the reported crystal structure is seen as a signal of "hey, if this turns out to be real, we can explain it with current physics." That's something that previous fraudulent claims of room temperature ambient pressure superconductors (University of Rochester group) couldn't do. The other interesting conclusion of the LBNL paper is that the low-energy physics of the electronic structure can be effectively modeled by a two-level effective Hamiltonian. This is a common pathway to bridging the gap between DFT calculations and theoretical understanding of strong correlations. None of the serious scientists are saying "hey, look, DFT predicted it so it's true." Rather, it doesn't rule it out, and it suggests that it could be understood with our current physics. That's significant in itself.
- tnecniv 3y agoFrom my understanding of DFT that makes sense but it seems like in that case you are using the wrong tool. Approximate theories are good when the approximations are good. If your phenomena is strongly correlated, throwing out those correlations is bad. I have no idea if the use of DFT here is appropriate or not.