Plenary Abstracts

Scaling quantum accuracy from DFT to MLIPs: Progress, Pitfalls, and Prospects
Brandon Wood, Meta

Recent years have seen rapid progress toward broadly transferable machine-learned interatomic potentials (MLIPs) that approach the accuracy of Density Functional Theory (DFT) reference data at a fraction of the computational cost. Yet developing models that are simultaneously fast, chemically accurate, and produce physically consistent simulations across diverse chemical spaces remains challenging. In this talk, I will survey recent advances and highlight key ingredients that have driven progress including data curation, model architecture choices, and evaluation strategies. I will present representative benchmarks in which models closely reproduce the reference level of theory and match or surpass commonly used DFT functionals, while also discussing known limitations and failure modes. I will conclude with perspectives on where the field is headed and where opportunities exist for both the chemistry and machine learning communities.

Title TBD
Boubacar Kante, University of California, Berkeley

Abstract TBD

Antimicrobial Peptoids Pass Rapidly Through Bacterial Membranes and Flocculate Ribosomes and DNA: A Single-Cell Fluorescence Study
Annelise Barron, Stanford University

In work nucleated at the LBNL Molecular Foundry, we have shown that certain peptoids designed as structural and functional mimics of host defense peptides such as LL-37 exhibit potent, broad-spectrum antibacterial, antifungal, antiparasitic, and antiviral activity with minimal cytotoxicity. Previous fixed-cell studies done at LBNL have suggested that the peptoids can pass through bacterial membranes and rapidly kill bacteria by aggregating intracellular macroanions, including ribosomes and DNA. However, the dynamic mechanisms of action of these biomimetic peptoids have remained elusive. We employed single-bacterial-cell, time-resolved fluorescence microscopy and single-particle tracking methods to investigate the effects of the 12mer peptoid TM1, along with shorter alkylated and brominated analogues, on cytoplasmic membrane permeabilization and DNA and ribosome rigidification of Escherichia coli. Our results demonstrate that peptoid TM1 and several of its analogues permeabilize the bacterial cytoplasmic membrane within 5 minutes of flowing the peptoid solution over the cells—faster than seen for the important human antimicrobial peptide LL-37—and rigidify DNA and ribosomes as effectively as LL-37. Detailed biophysical structural and dynamical studies show that TM1 binds to both DNA (double-stranded and single-stranded) and single-stranded RNA in a similar manner to LL-37, which is well known to display strong nucleic acid binding. These results support our hypothesis that TM1 and its analogues exert their antimicrobial effects through intracellular aggregation of biomacromolecules such as ribosomes, RNA, and DNA. TM1 displays a higher affinity for RNA compared to DNA, suggesting it will preferentially bind in vivo to bacterial ribosomes. Our study yields new insights into the dynamic effects of antimicrobial peptoids, facilitating their future development as biomimetic anti-infectives, with the additional advantage that peptoids offer of virtually complete invulnerability to proteases.

Freestanding oxide membranes and their heterostructures
Seung Sae Hong, University of California, Davis

Complex oxides host a wide range of electromagnetic phenomena—ferroelectricity, magnetism, metal-insulator transitions, and superconductivity—making them a central focus of modern condensed matter and materials research. Freestanding oxide membranes, synthesized as epitaxial thin films and released from their bulk substrates, represent an emerging class of low-dimensional materials. Free from substrate-imposed constraints, these membranes offer unprecedented opportunities to probe intrinsic material properties and engineer functional behavior in ways inaccessible to conventional thin-film platforms. This talk presents highlights from collaborative user projects that leverage this platform across three fronts: (1) probing the nature of ferroelectricity in oxide membranes, (2) visualizing heterogeneous phase evolution during topotactic phase transitions, and (3) elucidating atomic structures in twisted oxide membrane heterostructures. Together, these examples demonstrate how a multimodal suite of characterization tools—spanning optical spectroscopy to four-dimensional scanning transmission electron microscopy (4D-STEM)—can accelerate discovery in complex oxide research.

Functionalization of the Ends and Surfaces of Polyethylene
John Hartwig, University of California, Berkeley

The properties of polyethylene depend on the structure and composition of the bulk material and the surface. We have developed a series of reactions that install functional groups on the chains of polyethylene and alter the properties of these polymers. These reactions encompass oxidation, amination and borylation of various classes of polyethylenes. Now, we have sought to control the position of this functionalization at both the molecular and macroscopic level. Functionalization in solution or the melt at random positions along the chain should lead to polymers with different material properties than functionalization of a surface or functionalization at chain ends. This talk will present results on the catalytic oxidation of the surface and catalytic borylation of the chain ends of polyethylene. A variety of measurements of the properties of these materials at the Molecular Foundry show how this positional selectivity leads to independent control of bulk and surface properties of the material.

High-Q-factor chiral metasurfaces for twist control of electrons and photons
Feng Pan, Stanford University

Spin is one of the most fundamental properties of elementary particles. Photons, possessing spin angular momentum (circular polarization), typically exhibit long spin coherence times but inherently weak coupling to their environment. Efficiently harnessing circularly polarized light for quantum information systems thus demands exceptional control and manipulation of chiral light-matter interactions (LMIs). Here, we describe high-Q-quality chiral metasurfaces to enhance linear and nonlinear chiral LMIs for realizing solid-state, optically addressable spin qubits and chiral quantum light emission. These metasurfaces achieve high-Q chiroptical resonances by breaking both in-plane inversion and mirror symmetries, resulting in nonlocal chiral quasi-bound states in the continuum (q-BICs). First, we demonstrate a scalable, large area Si-MoSe2 heterostructured platform in which the chiral q BIC is engineered to match the MoSe2 A exciton (~770 nm). The crystalline Si chiroptical cavities yield Q factors of several hundred and enable simultaneous control of valley specific emission spectra and far field radiation. We observe robust valley selective emission against excitation polarization states, reaching a record high degree of circular polarization of 0.5 at room temperature. Second, we introduce a high Q-factor AlGaAs nonlinear chiroptical cavity for spontaneous parametric down conversion that generates non degenerate entangled photon pairs encoded with spin angular momentum (SAM). Our work shows photon-pair generation rates reaching up to 106 Hz—four orders of magnitude higher than conventional nanoantenna structures. Overall, these results establish high Q-factor chiral nanophotonic platforms as versatile tools for light-driven control of functional materials, enabling highly efficient room-temperature electron-photon spin transduction and SAM-encoded entangled photon-pair generation.

Atomic-Scale Binary Oxide Films for Energy-Efficient and Energy-Autonomous Computing Chips
Koushik Das, University of California, Berkeley

Due to the rapid increase in computing demand and energy consumption, energy efficiency in electronics has become a defining challenge for sustainable progress in AI, IoT, Data Centers, and beyond. Achieving these advances, however, requires simultaneous innovation in materials, transport physics, and device engineering. In this seminar, I will discuss how atomic-scale engineering can uncover and harness previously unexplored ferroic order in scalable, foundry-compatible binary oxides and integrate them with state-of-the-art device technologies for the advancement of energy-efficient computing chips. We have demonstrated its application in stabilizing negative capacitance, a novel phenomenon present in ferroelectric materials which enables energy-efficient nanoscale transistors and in developing low-power non-volatile memory operation. Furthermore, its application for on-chip energy storage, which is several orders faster than commercial Li-ion micro-batteries. In closing, I will discuss how emerging functionalities in binary oxides can spawn future directions for energy-efficient and energy-autonomous microelectronics.