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COSMO Lab

@labcosmo.bsky.social
1.3K followers 196 following 184 posts

Computational Science and Modelling of materials and molecules at the atomic-scale, with machine learning.

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Reposted by COSMO Lab
marcel ⊙ @marceldotsci.bsky.social · 18/09/2026
✨ new work: "Truncated automatic sparse differentiation for MLIPs" with @adrianhill.de & @micheleceriotti.bsky.social has arrived on the arXiv. In a 🥥: we exploit that MLIP Hessians are sparse and decay with distance with a "truncated" variant of automatic sparse differentiation. See figure. 👇
Truncated automatic sparse differentiation (ASD). (a) Toy chain of 7 atoms, model reach K = 2 hops. The Hessian H is recovered from Hessian-vector products (HVPs) with the columns of a seed matrix S, giving the compressed product HS. Since H is sparse, star coloring needs 5 colors, hence 5 HVPs instead of 7. Each entry of H is read from one entry of HS (its hue), directly or via its symmetric partner; entries that are sums are never read (crossed). Truncating to one hop needs only 3 HVPs, but the neglected two-hop couplings (gray) now contaminate entries that are read (dots), causing errors. (b) MOF-177 with PET-XS: atoms within K = 5 hops of one Zn atom in the model's graph, with its cutoff sphere and one-hop edges; rest of the cell in gray. (c) Same atoms colored by the force-constant block norm ‖Φᵢⱼ‖ to the marked atom, decaying with distance. (d) Whole Hessian of MOF-177, one cell per atom pair, graph neighbors adjacent: hop count above the diagonal, ‖Φᵢⱼ‖ below, zeros white.
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Reposted by COSMO Lab
Matthias Kellner @matthiaskellner.bsky.social · 18/09/2026
We have released ShiftML4! ShiftML4 comes with built-in molecular corrections, elevating the chemical shielding predictions to hybrid-DFT level quality. Try it yourself on shiftml.org, or from the PyPi package.
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COSMO Lab @labcosmo.bsky.social · 02/08/2026
True, but the converse is also true, and probably part of the issue: the equivariant representations we use can represent any function, not only an atom density, so they might end to be also wasteful in a certain sense.
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COSMO Lab @labcosmo.bsky.social · 30/07/2026
A little holiday reading from 🧑‍🚀: arxiv.org/html/2607.26... , or how Michelangelo used #AI to break equivariant atom-centered descriptors all the way to 7 neighbors (and arbitrary many neighbors when considering a finite, practical level of discretization). 🤯
Atomic structures that are indistinguishable by atom-centered descriptors for ML potentials
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COSMO Lab @labcosmo.bsky.social · 02/07/2026
What will O2, benzene and ozone do on top of a Mendeleev cluster 🤔 ? Thanks to the improved mlip.js webtool from Peter Spackman you can figure it out running #PET-MAD-XS in your browser using webgpu 🚀 . Try it out at @crystalexplorer.net 's amazing MLIP.js peterspackman.github.io/mlip.cpp/
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COSMO Lab @labcosmo.bsky.social · 12/06/2026
Thanks you for coordinating, to Marnik for the past midnight virtual machine updates, and on our end to the COSMO team which prepared and delivered the tutorials, which you can find on atomistic-cookbook.org
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COSMO Lab @labcosmo.bsky.social · 11/06/2026
It's agreement on sampling and dynamics with the reference small timestep MD
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COSMO Lab @labcosmo.bsky.social · 10/06/2026
You can read more about this little gem from 🧑‍🚀 @filippobigi.bsky.social and Johannes Spies here journals.aps.org/prl/abstract..., and a popular summary on phys.org, physics.aps.org/articles/v19....
journals.aps.org
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COSMO Lab @labcosmo.bsky.social · 10/06/2026
TL;DR - this allows running molecular dynamics with much longer time steps, ensuring long-time stability of the trajectories. The method is a true beauty, extremely elegant, although not super-practical - we see it more as a correction to make sure that flashmd.org ⚡ trajectories are working well.
flashmd.org
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COSMO Lab @labcosmo.bsky.social · 10/06/2026
Time to learn the action 🏃 ! Today I'm sharing a paper, just published on @physrevlett.bsky.social, showing how to construct a symplectic #machinelearning predictor of classical mechanics by learning the Hamilton-Jacobi action.
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COSMO Lab @labcosmo.bsky.social · 09/06/2026
Afternoon action at the @nccr-marvel.bsky.social / @ictp.bsky.social summer school, with the 🧑‍🚀 team introducing MD with #machinelearning potentials using PET, metatomic and the atomistic-cookbook.org 🧑‍🍳📖
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COSMO Lab @labcosmo.bsky.social · 02/06/2026
Kudos to Sofiia Chorna who has taken over as lead developer, @luthaf.bsky.social, @cersonsky.bsky.social , @jakublala.bsky.social and Qianjun Xu to help turn a weekend project into a super-useful tool.
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COSMO Lab @labcosmo.bsky.social · 02/06/2026
On the web, in your jupyter notebooks, in online documentations and in streamlit applications, every time you have to look at atomic-scale data, chemiscope is there to help.
chemiscope 1.0 can be used online, in jubyter notebooks, in documentation pages and in streamlit apps
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COSMO Lab @labcosmo.bsky.social · 02/06/2026
📢 Chemiscope 1.0 paper is out on #JOSS. If you haven't used ⚗️ 🔭 recently, head to joss.theoj.org/papers/10.21... to read a summary of the new features, to chemiscope.org to try it out, and type `pip install chemiscope` to use it locally.
chemiscope.org
Chemiscope
Interactive data visualization for materials and molecular databases. Correlate atomic structures and their properties, either online, in a jupyter notebook, or with a portable app.
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COSMO Lab @labcosmo.bsky.social · 03/03/2026
If this sounds too good to be true, don't believe me, see for yourself: there is already a 🧑‍🍳 📖 recipe waiting for you try atomistic-cookbook.org/examples/men...
atomistic-cookbook.org
Mendeleev’s nano-clusters - The Atomistic Cookbook
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COSMO Lab @labcosmo.bsky.social · 03/03/2026
The simulation is stable for a combined 1.6 ns, and the final structures make a lot of physical sense: noble gases, and at higher temperature more volatile stuff, leave the particle. Accuracy is quantitative: the MAE error on forces is ~150 meV/Å - pretty exceptional for something so outlandish!
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COSMO Lab @labcosmo.bsky.social · 03/03/2026
So let us show you just how *universal* #PET-MAD-1.5 can be. This is a movie of a parallel tempering simulation, with replicas from 300K to 3000K, of what we call a "Mendeleev cluster" - one atom each of every element from 1 to 102.
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COSMO Lab @labcosmo.bsky.social · 03/03/2026
Looking forward to see what you do with the dataset, MAD-1.5, and the universal potential, PET-MAD-1.5! 🔗: 📄 arxiv.org/html/2603.02...; 🚀 github.com/lab-cosmo/up...
arxiv.org
High-quality, high-information datasets for universal atomistic machine learning
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COSMO Lab @labcosmo.bsky.social · 03/03/2026
This is the result of a massive effort by @cesaremalosso.bsky.social, @filippobigi.bsky.social, @ppegolo.bsky.social, @jwasci.bsky.social, @mahrossi.bsky.social and Arslan Mazitov, as well as all the 🧑‍🚀 working tirelessly on the conceptual and software infrastructure.
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COSMO Lab @labcosmo.bsky.social · 03/03/2026
Now, this is just a milestone on that path, but it's already something worth sharing, so thanks to arXiv you can read about it arxiv.org/html/2603.02..., and thanks to uPET github.com/lab-cosmo/up... and metatomic, you can try already a universal MLIP trained on it.
github.com
GitHub - lab-cosmo/upet: Universal interatomic potentials for advanced materials modeling
Universal interatomic potentials for advanced materials modeling - lab-cosmo/upet
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COSMO Lab @labcosmo.bsky.social · 03/03/2026
📢 We have been working on a new universal atomistic dataset that combines the principles of MAD with a meta-GGA level of theory, so we can all simulate water that does not freeze at 500K 🧊 , and have all our bases covered, with reference data for every isotope with a half-life above 24 hours ☢️
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COSMO Lab @labcosmo.bsky.social · 23/02/2026
New recipe just landed on the atomistic-cookbook.org 🧑‍🍳📖. Thanks to @yairlitman.bsky.social for explaining how to use ipi-code.org to perform ring-polymer instanton calculations of reaction rates that include quantum tunneling effects ⚛️⚡. Check it out 👉 atomistic-cookbook.org/examples/rin...
Snapshot of a ring-polymer instanton calculation for the reaction of methane with a H radical
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COSMO Lab @labcosmo.bsky.social · 18/02/2026
📢 New #preprint is out! Investigating the many flavors of last-layer #UQ, Moritz and 🧑‍🚀Matthias propose a practitioners' guide on "how to train a shallow ensemble". TL;DR? for good calibration use NLL, include force, and optimize the backbone, fine-tuning for speed! 📃🔗➡️ arxiv.org/html/2602.15...
arxiv.org
How to Train a Shallow Ensemble
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COSMO Lab @labcosmo.bsky.social · 17/02/2026
welcome!
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COSMO Lab @labcosmo.bsky.social · 14/02/2026
... but it is too inflexible to learn highly-correlated fragment energies, and does not extrapolate well to different densities. If you are curious to learn more, read the whole story here pubs.aip.org/aip/jcp/arti...
pubs.aip.org
Resolving the body-order paradox of machine learning interatomic potentials
In many cases, the predictions of machine learning interatomic potentials (MLIPs) can be interpreted as a sum of body-ordered contributions, which is explicit w
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COSMO Lab @labcosmo.bsky.social · 14/02/2026
Our conclusion is that the body ordered decomposition is not a very useful prior for conditioning MLIPs. An architecture such as MACE that forces a fast-converging effective decomposition learns well in the low-data regime ...
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COSMO Lab @labcosmo.bsky.social · 14/02/2026
Last but not least, of the architectures we tried, only PET 😸 could actually do something good out of learning these fragments, while MACE sees its extrapolative power degrade significantly when forced to learn the slowly-converging vacuum cluster expansion.
Interpolative and extrapolative performance of different architectures for intermediate H cluster densities, with and without fragments included into training.
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COSMO Lab @labcosmo.bsky.social · 14/02/2026
Third, only architectures with sufficient expressive power, such as MACE or PET, can learn the true expansion, when exposed to fragments in the training set.
Changes in the learned expansion as the fraction of fragments added to the training set is increased
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COSMO Lab @labcosmo.bsky.social · 14/02/2026
This is a story with many layers. First, the quantum cluster expansion does not converge, mostly because the fragments have crazy geometries and highly-correlated electronic structure. Second, MLIPs exposed only to compact structures learn their own effective body-ordered decomposition.
Body-ordered energy decomposition for low and high-density hydrogen clustersBody-ordered energy decomposition for different MLIP architectures. None learns spontaneously the "true" decomposition
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COSMO Lab @labcosmo.bsky.social · 14/02/2026
A 🧑‍🚀 dream team led by Sanggyu Chong, with some FCI help from Joonho Lee @harvard.edu, tries to answer this question, and to understand what it implies for the accuracy and transferability of MLIPs in this new 📄 fresh off the press at @aip.bsky.social #JCP. pubs.aip.org/aip/jcp/arti...
pubs.aip.org
Resolving the body-order paradox of machine learning interatomic potentials
In many cases, the predictions of machine learning interatomic potentials (MLIPs) can be interpreted as a sum of body-ordered contributions, which is explicit w
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COSMO Lab @labcosmo.bsky.social · 14/02/2026
Many #machinelearning potentials are built (or understood) in terms of "atomic cluster expansions" that link directly to a body-ordered energy decomposition that can be computed explicitly with a sequence of electronic structure calculations. But what kind of expansion do they learn in practice? A🧵
The body ordered expansion, equations
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COSMO Lab @labcosmo.bsky.social · 13/02/2026
Hot off the press on hashtag @aip.bsky.social #JCP, an introduction to the metatensor ecosystem. High-quality 🧑‍🚀 tools for atomistic hashtag#machinelearning - read on pubs.aip.org/aip/jcp/arti... and check it out at metatensor.org 🧑‍🍳 📖 recipes here atomistic-cookbook.org/software/met...
pubs.aip.org
metatensor and metatomic: Foundational libraries for interoperable atomistic machine learning
Incorporation of machine learning (ML) techniques into atomic-scale modeling has proven to be an extremely effective strategy to improve the accuracy and reduce
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COSMO Lab @labcosmo.bsky.social · 12/02/2026
It is a stormy day, but the COSMO retreat is going strong!
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COSMO Lab @labcosmo.bsky.social · 09/02/2026
🧑‍🚀 Filippo, Arslan and Paolo doing some PET talk with our friends at the @epfl-ai-center.bsky.social ai.epfl.ch/a-new-refere...
ai.epfl.ch
A New Reference Model for Machine-Learning–Driven Materials Discovery - EPFL AI Center
Researchers at EPFL’s Laboratory of Computational Science and Modeling (COSMO) have reached a significant milestone in material science, reaching the top position on Matbench Discovery, the leading be...
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COSMO Lab @labcosmo.bsky.social · 08/02/2026
If you want to learn about materials modeling, from DFT to MD, well marinated in a spicy ML sauce, don't miss out the @ictp.bsky.social / @nccr-marvel.bsky.social college. Details and application instructions here indico.ictp.it/event/11146/. See you in Miramare!
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COSMO Lab @labcosmo.bsky.social · 06/02/2026
PET continues its victory round of benchmarks and challenges 🥇🥉. And this one has a (bit far-fetched) end goal that would also make it useful! Congrats to Filippo and Cesare (and @marceldotsci.bsky.social who got a honorable mention and will also try further his LOREM model)🚀 dtu.dk/english/news...
dtu.dk
International AI competition aims to speed up the development of materials for the green transition
The Pioneer Center CAPeX at DTU has announced the winners of the first phase (Stage 1) an international competition in partnership with the Novo Nordisk Foundation, and the Danish Centre for AI Innovation (DCAI), on using machine learning models to predict synthesis recipes for novel nanoparticles.
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COSMO Lab @labcosmo.bsky.social · 03/02/2026
Congratulations to 🧑‍🚀 Sergey Pozdnyakov who very deservedly won the @materials-epfl.bsky.social doctoral distinction award. A good time to go check on his papers, if you haven't read them already!
Sergey collects the edmx doctoral distinction prize
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COSMO Lab @labcosmo.bsky.social · 01/02/2026
Release candidate 3 of chemiscope 1.0 is out, with class and range based highlighting of points. Try it, break it, report it on github.com/lab-cosmo/ch...
Cluster highlights in chemiscope 1.0 RC3
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COSMO Lab @labcosmo.bsky.social · 30/01/2026
Fantastic news from the @snf-fns.ch, who despite the budget cuts managed to fund six new NCCRs. Looking forward to doing some cool simulations to advance separation science! actu.epfl.ch/news/a-new-n...
actu.epfl.ch
A new national research programme recognizes EPFL's expertise
The Swiss Confederation launches six new National Centres of Competence in Research (NCCRs). The NCCR “Separations”, which aims to accelerate research in separation sciences - the quest for chemical a...
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COSMO Lab @labcosmo.bsky.social · 23/01/2026
If you're scared by the 700M parameters (you shouldn't be) there's a whole set of models from 🐁 to 🦣. You can find them all on github.com/lab-cosmo/upet !
Pareto front for PET-OMAT models
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COSMO Lab @labcosmo.bsky.social · 23/01/2026
If you got curious by the PET-OAM results a week ago, you can learn more reading up arxiv.org/abs/2601.16195. Including some general considerations on how to train and use safely an unconstrained ML potential.
Table showing results of a few representative universal model on the matbench leaderboard
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COSMO Lab @labcosmo.bsky.social · 14/01/2026
You can fetch the model here github.com/lab-cosmo/upet, as easy as `pip install upet`, and then, for the ASE interface, `from upet.calculator import UPETCalculator; calculator = UPETCalculator(model="pet-oam-xl", version="1.0.0", device="cuda")` Have fun and go break it!
github.com
GitHub - lab-cosmo/upet: Universal interatomic potentials for advanced materials modeling
Universal interatomic potentials for advanced materials modeling - lab-cosmo/upet
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COSMO Lab @labcosmo.bsky.social · 14/01/2026
Not going to make a big deal out of a benchmark table, but PET just got the top spot on matbench-discovery.materialsproject.org. And don't be fooled by the huge parameters count, it's faster and can handle larger structures than eSEN-30M 🚀. Kudos to 🧑‍🚀 Filippo, Arslan and Paolo!
Screenshot of the matbench discovery leaderboard as of 14.01.2026, showing a PET based model in the top position
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COSMO Lab @labcosmo.bsky.social · 05/01/2026
📢 chemiscope.org 1.0.0rc1 just dropped on pypi! We are making (a few) breaking changes to the interfaces, fixing a ton of bugs and introducing some exciting features (you can finally load datasets with > 100k points!). We'd be grateful if you test, break and report 🐛 github.com/lab-cosmo/ch...
Zooming in on a large-scale dataset to showcase the new adaptive resolution features in chemiscope
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COSMO Lab @labcosmo.bsky.social · 03/01/2026
Hope y'all are getting a great start of 2026. Here we're taking some time to add the 2025 winter card to the archives www.epfl.ch/labs/cosmo/i... 🎅=🧑‍🚀
A cheeshire cat sitting on a tree overlooking a winter landscape, with snapshots of the many classes of materials that the PET-MAD universal interatomic potential can be used for
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COSMO Lab @labcosmo.bsky.social · 18/12/2025
Ah, a fine example of a `for regressor in sklearn.supervised_learning:` paper. It's an underappreciated genre.
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COSMO Lab @labcosmo.bsky.social · 17/12/2025
📢 New chemiscope.org release just landed! To make it even easier to integrate ⚗️🔭 into your workflow, we added a @streamlit.bsky.social component, so you can run analyses and show you atomistic data in a web app by just writing a few lines of python! try it, break it, report it!
example of a streamlit app integrating a chemiscope viewer
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COSMO Lab @labcosmo.bsky.social · 10/12/2025
Congrats to 🧑‍🚀 Sergey Pozdnyakov who received a distinction (best 8% of theses at @materials-epfl.bsky.social) for his PhD thesis "Advancing understanding and practical performance of machine learning interatomic potentials". Поїхали 🚀! infoscience.epfl.ch/entities/pub...
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COSMO Lab @labcosmo.bsky.social · 09/12/2025
No day goes by without a new universal #ML potential. But how different they really are? Sanggyu and Sofiia tried to give a quantitative answer by comparing the reconstruction errors between their latent-space features. If you are curious, check out the #preprint arxiv.org/html/2512.05...
Features reconstruction errors between the latent spaces of several universal MLIPs
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COSMO Lab @labcosmo.bsky.social · 28/11/2025
Oh. My. Gawd. ☝️☝️☝️☝️ 👀
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