Paesani Lab

🚨 #MBX is now officially part of the *release* branch of #LAMMPS! 🚨 👉 github.com/lammps/lammps/… #MBX is our group’s C++ engine for #datadriven #manybody potentials (including MB-pol / MB-nrg) and is now distributed directly with #LAMMPS as an official package. What this means: ✅ Standard #LAMMPS installation at build time ✅ Native integration via pair_style mbx ✅ Seamless use of available #datadriven #manybody potentials (see mbxsimulations.com for a list) with #LAMMPS integrators, thermostats, barostats, constraints, and analysis tools. To make it easy to get started, we’re launching a new series of #MBX+#LAMMPS video tutorials. 🎬 First video: Installation guide 👉 youtube.com/watch?v=BBlq2R… Questions or feedback? Join the discussion: 👉 groups.google.com/g/mbx-users Huge thanks to the #LAMMPS developers and the #MBX team for making this happen! 🙌 🙏 Big thanks also to @NSF for supporting this effort! @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD

That’s a wrap on #APSSummit2026! @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD @aps

🚨 Excited to share that our Annual Review of Physical Chemistry article is now online! 👉 go.shr.lc/4sRLQSs #Water has long posed a fundamental challenge in molecular simulation: Is it possible to build a molecular model that realistically reproduces its properties across all phases? 🤔 That question motivated the development of MB-pol, which showed that a #datadriven #manybody potential can describe #water with remarkable realism from gas-phase clusters 🫧 to the liquid phase 🌊, and ice 🧊. We then generalized that framework to MB-nrg, extending predictive #datadriven #manybody simulations to #ions and revealing how they reorganize the structure, thermodynamics, dynamics, and vibrational spectra of water across different phases.⚡️ Our journey also led to #MBX, our software that makes #datadriven #manybody simulations practical for increasingly complex molecular systems.🖥️ We tell the full story in this review and provide a glimpse of where #datadriven #manybody simulations are headed next. We hope you enjoy reading it! 🙂 @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD

We landed in Denver for the #APSSummit2026! Quite a change from sunny San Diego 🌞, but the snow ❄️ didn’t stop us from exploring the neighborhood before the meeting begins. Our group will present several talks on water clusters, solvated #ions, the #air/#water interface, #nanoconfined water, and #datadriven #manybody simulations of #biomolecules. Looking forward to a few days of exciting #science! @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD @APSphysics

New in @JCIM_JCTC : GPU-accelerated ESP in QUICK + new rwRESP removes grid sensitivity for robust RESP charges. Available in AmberTools. Paper: doi.org/10.1021/acs.jc… #CompChem #GPU #OpenSource

Women in #datadriven #manybody simulations for chemistry, biology, physics, materials science, and beyond! Today we celebrate the brilliant women in our group whose curiosity, creativity, rigor, and leadership drive our #science forward every day. Across disciplines and across scales, they are helping shape the future of discovery. We’re proud to work alongside you, learn from you, and celebrate you, today and every day. Here’s to more breakthroughs, more visibility, and more women shaping the future of science. Happy #InternationalWomensDay! #IWD2026 #WomenInSTEM #WomenInScience @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD

It was a fantastic day welcoming prospective #PhD students to @UCSDChemBiochem! 🔬 Everyone had a great time exploring the science happening across the department, including our poster on the development and applications of #datadriven #manybody potentials for realistic molecular simulations. 🖥️ And of course, no visit to @UCSanDiego would be complete without a #LaJolla sunset by the #Pacific. 🌅 Good luck to everyone as you make your decision. This is an exciting time, and we hope to see many of you back here soon! 🙂 @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD

🚨 New preprint on @ChemRxiv! 🚨 Can a molecular model trained ONLY on the many-body expansion (#MBE) derived from CCSD(T) reference data predict bulk ion hydration thermodynamics without fitting to hydration free energies or bulk solution structure? 🤔 We show that our #datadriven #manybody MB-nrg potentials can! 😎 👉 chemrxiv.org/doi/full/10.26… Method A staged alchemical cycle that turns on the physics step-by-step: ✅ auxiliary vdW → charge → polarization → explicit 2B → explicit 3B ✅ then remove the reference vdW ✅ finite-difference thermodynamic integration and #PIMD mass-scaling for #NuclearQuantumEffects. Results 🎯 Correct monotonic weakening of hydration with increasing ion size (cations + anions). 🎯 Close agreement with experiment when comparing within-series reference differences (ΔΔG). 🎯 #NuclearQuantumEffects are modest but slightly improve the trends. Take-home message Hydration thermodynamics naturally emerges from a rigorous representation of many-body interactions without requiring fitting to bulk solvation data. 🚀 Huge congrats to Suman (@SSuman_24) for leading this project! 🙌 🙏 Big thanks to @NSF for funding and to @ACCESSforCI and @NERSCfor providing computational resources! @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD

🚨 New paper out in @JPhysChem Lett.! 🚨 We're excited to share our latest work (a collaboration with @BonnMischa's group at @mpi_polymer): 👉 pubs.acs.org/doi/10.1021/ac… At the #air/#water interface, "free" (dangling) O–H groups are responsible for a sharp peak at ~3700 cm⁻¹ in the vibrational sum-frequency generation (#vSFG) spectrum.⚡️ Because it’s so narrow, it’s often treated as spectrally #homogeneous. But is it really? 🌊 In this study, we combine: ✅ Three distinct polarization‑resolved heterodyne‑detected #vSFG measurements, reporting the first #SPS spectrum. ✅ Our #datadriven #manybody MB-pol potential for predictive simulations. ✅ Path‑integral-based quantum dynamics (Te‑PIGS) simulations to capture #NuclearQuantumEffects. Our key findings: 🎯 The free O–H peak shifts with polarization by ~13–15 cm⁻¹ → direct evidence that *orientation matters* even for “free” O–H. 🎯 Free O–H bonds tilted toward the interfacial plane are systematically red‑shifted compared to more upright O–H. 🎯 Mechanism: orientation‑dependent *local electric fields* from neighboring water molecules. Stronger projected fields along the O–H axis correlate with lower (red‑shifted) fundamental frequencies. Take‑home message: 🔎 A sharp peak ≠ a uniform interface. The #water surface is intrinsically heterogeneous, and polarization‑resolved spectroscopy + quantum many‑body simulations can read out that heterogeneity in terms of local electric fields. Huge congrats to #Richa for leading this project! 🙌 🙏 Big thanks to @NSF for funding and to @ACCESSforCI and @NERSC for providing computational resources! @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD

A molecule has its own unmistakable tone, but the voices of single molecules are so faint that traditional infrared spectroscopy can't detect them. @UCSDChemBiochem prof Shaowei Li has found a way to hear a single molecule sing. bit.ly/46RiTgP

‘Many important moments in my career seemed entirely serendipitous, but sharing of ideas, collaboration and building of community was important to my work.’ chemistryworld.com/opinion/veroni…

Huge congratulations to Prof. Shaowei Li and team on their @ScienceMagazine paper! 🎉 Single-molecule infrared spectroscopy with STM captures vibrational modes with atomic precision, opening a new era in bond-specific chemistry. @UCSanDiego @UCSDPhySci science.org/eprint/INVDJBZ…

@Mattia__Serra Congratulations! 🙌

Honored to receive the 2026 Sloan Fellowship in Physics. I’m grateful to my mentors, my research group, and those who supported my nomination. Thank you! #SloanFellow

🚨 New paper out in @JPhysChem Lett.! 🚨 We are excited to share our latest work: 👉 pubs.acs.org/doi/10.1021/ac… Interfacial #water behaves very differently from bulk #water. 🌊 At charged interfaces, interpreting vibrational sum-frequency generation (#vSFG) spectra becomes particularly challenging. ⚡️ The key question is: 🤔 What is truly “surface-specific” (χ²), and what originates from bulk field-induced contributions (χ³)? In this study, we combine: ✅ Our #datadriven #manybody MB-pol potential ✅ Temperature-elevated path-integral coarse-graining (Te-PIGS) to include #NuclearQuantumEffects ✅ Layer-resolved heterodyne-detected #vSFG simulations to provide a molecular-level separation of χ² and χ³ contributions at charged graphene oxide/water (#GO/#water) interfaces Our findings: 🎯 The prominent ~3200 cm⁻¹ band observed experimentally is not primarily surface-specific. It is dominated by field-induced bulk χ³ mixing associated with the electrical double layer. 🎯 In contrast, the strictly interfacial structure is encoded in χ². 🎯 This explicit χ²/χ³ decomposition clarifies how surface and bulk responses combine to shape measured #vSFG spectra at charged aqueous interfaces. Beyond #GO, this framework provides a general strategy to interpret vibrational spectra at charged and nanoconfined aqueous interfaces, with implications for: • Membrane science • Electrochemical systems • Sensing platforms • Interfacial reactivity Congratulations to #Toheeb and #Richa for leading this exciting collaboration between our groups at @UCSanDiego and @LSU! 🙌 Excited to see how heterodyne #vSFG experiments will further test these predictions. 🚀 @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD @LSU_Chemistry

Yesterday we had a fantastic time at the 8th #SoCalTheoChem Symposium at @csuf (huge thanks to @csufchembiochem)! 👉 sites.google.com/fullerton.edu/… It was great to catch up with the SoCal theoretical chemistry community and present our research on #datadriven #manybody simulations 🖥️ for vibrational spectroscopy 🔦, dispersion energy ⚡️, biomolecules 🧬, and MOFs 🧪. Special shoutout to our former #PhD student Teri, now an Assistant Professor at @csuf, for an exciting first official talk! @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD

@RandallSnurr Thanks so much @RandallSnurr! Really appreciate the kind words!🙏 #MBX ↔️ #RASPA integration is also coming together nicely, and we’ll share an update soon 🙂

@PaesaniLab This *is* big news. Congratulations and thank you!

🚀 Big news from our group: #MBX is officially on its way into #LAMMPS! 🎉 👉 github.com/lammps/lammps #MBX is already available in the #LAMMPS *develop* branch on #GitHub, and will soon be available on the *release* and eventually *stable* branches. If you want to try out the development version now, we have instructions on our Google Group: groups.google.com/u/1/g/mbx-user… What this means (and why it’s exciting): ✅ #MBX is becoming an official #LAMMPS package → easy installation at build time like any other package. ✅ Seamless integration with the #LAMMPS ecosystem → you can keep using your standard simulation protocols (NVE/NVT/NPT, constraints, etc. via #LAMMPS “fix” commands, not yet the ELECTRODE package) while running available #datadriven #manybody potentials powered by #MBX (see full list at mbxsimulations.com/tutorials/pefs…). ✅ Expanded and improved documentation at docs.lammps.org/latest/pair_mb…. Stay tuned for further developments and new #datadriven #manybody potentials! 🔥 Congratulations to the #MBX team! @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD

🚨 New preprint on @ChemRxiv! 👉 doi.org/10.26434/chemr… How does *each added water molecule* reshape an amino acid’s hydrogen‑bonding + vibrational fingerprints? To address this question, we: ✅ developed a #datadriven #manybody (MB-nrg) potential for GlyH⁺–H₂O 🧬🌊 ✅ combined replica-exchange sampling with quantum path-integral dynamics to capture nuclear quantum effects 😎 ✅ applied inverse spectral reconstruction to directly connect experimental cryogenic #IR spectra to specific hydration motifs + their populations ⚡️ ✨ Key takeaway: the first solvation shell of GlyH⁺ “clicks” into place at n = 4, with three waters around −NH₃⁺ and one at −COOH. Additional waters primarily build the second shell. 🎉 Huge congratulations to Zoe, our amazing undergraduate, on her #first first-author paper. What a milestone! Stay tuned for more #datadriven #manybody biosimulations! 🚀 🙏 Big thanks to @NSF for funding and @ACCESSforCI for computational resources. 🖥️ @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD

We are beyond proud to share a story about our brilliant #PhD student Cianna and why public universities matter. 🏛️ 👉 #cianna" target="_blank" rel="nofollow noopener">universityofcalifornia.edu/news/uc-change… Cianna survived a life‑threatening medical crisis thanks to the extraordinary doctors, nurses, and staff of @ucsdpccm at @UCSDHealth Jacobs Medical Center. That is the common good in action: public investment in education and health care saving live. 💙 Today, Cianna is back at the frontier of #ProteinDesign and #ComputationalChemistry. Her latest paper uses molecular simulations to understand how threonine ladders behave on β‑solenoid scaffolds. The insights she gained are now guiding the design of de novo antifreeze proteins with applications from biomedical #Cryopreservation to #FoodScience. Stay tuned! 🧬 Read Cianna's paper: 👉 pubs.acs.org/doi/10.1021/ac… Keep an eye on Cianna’s research (and remember her name). She’s on a path to making impactful contributions to science and society! 🚀 @UofCalifornia @UCSanDiego @UCSDPhySci @UCSDChemBiochem @HDSIUCSD @SDSC_UCSD @UCSDMedSchool