Materials Science
Identification and Prediction of Photoplasticity in Semiconductors Using Feature Engineering and Machine learning
Huicong Chen, Mingqiang Li, Zheyuan Ji et al. (+1 more)
Photoplasticity, the light-induced change in plastic deformation, plays a pivotal role in the mechanical durability and manufacturing of
semiconductor materials. Yet, its governing mechanisms remain incompletely understood, owing to the interplay of coupled multiphysics factors. Here, we conduct high-throughput nanoindentation measurements to compile a
dataset of paired hardness values in dark and light conditions. Then, we engineer physics-informed descriptors spanning electrical, mechanical, and optical properties, and identify the ten most informative features, including bandgap, breakdown field, and refractive index, to enable an interpretable machine learning framework that yields transferable design rules for light-tunable
semiconductor mechanics. By identifying and predicting photoplasticity in
semiconductors, this work provides a practical pathway for extracting mechanism-linked, transferable guidelines to engineer light-responsive mechanical behavior in
semiconductor materials and devices.
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All authors Huicong Chen, Mingqiang Li, Zheyuan Ji, Yu Zou
Materials Science
Alloying Controlled Tuning of Interfacial Spin Orbit Interaction and Magnetic Damping in Crystalline FeCo Alloys
Hongrui Lao, Matthias Kronseder, Zhe Yuan et al. (+5 more)
The discovery of intrinsic
spin orbit fields in noncentrosymmetric ferromagnets has attracted considerable interest for both fundamental studies and technological applications. However, once such materials are synthesized, the strength of the
spin orbit fields is difficult to tune because it is primarily a bulk property. Here, we demonstrate that the interfacial
spin orbit interaction (SOI) in single crystalline FeCo thin films grown on GaAs(001) can be continuously tuned via alloying. Using
spin orbit
ferromagnetic resonance, we find that the Lande g factor, the Gilbert damping (alpha), and the interfacial
spin orbit fields exhibit a common nonmonotonic dependence on Co concentration. A pronounced minimum occurs near x ~ 0.2 where an ultra low damping alpha ~ 0.0015 is achieved. Furthermore, we observe linear scaling between alpha and (g-2)^2, establishing a direct correlation between interfacial SOI and
magnetic relaxation. These results identify alloying as an effective knob to engineer interfacial SOI and damping in single crystalline ferromagnet
semiconductor heterostructures.
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All authors Hongrui Lao, Matthias Kronseder, Zhe Yuan, Thomas Narr, Thomas N. G. Meier, Nadine Mundigl, Christian H. Back, Lin Chen
Materials Science
Current-tunable room temperature ferromagnetism and current-driven phase transitions
Jianping Guo, Peng Rao, Xinhao Huang et al. (+9 more)
It is generally assumed that the application of a charge-current in
ferromagnetic metals suppresses their
ferromagnetic order through trivial Joule heating. Here, we demonstrate that a charge current can instead enhance
magnetic ordering. Using a WTe2/Fe3Ge2Te (FGT) stack as a model system, we show that a charge current flowing in WTe2 controls the
ferromagnetic properties and
magnetic phase transition of the adjacent FGT via a current-induced effective
magnetic-field arising from orbital magnetization. Remarkably, the charge current drives a substantial enhancement of the Curie temperature, boosting it well above room temperature. Furthermore, we show that the charge-current enables controlled tuning of the phase transitions in FGT, which confirms the scaling behaviour of a ferromagnet-paramagnet phase transition. This work provides a pathway for integrating two-dimensional ferromagnets into spintronic functionalities at technologically relevant temperatures and for exploring novel current-driven phenomena in
ferromagnetic systems.
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All authors Jianping Guo, Peng Rao, Xinhao Huang, Tailai Xu, Yuxuan Guo, Jian Shao, Cheng Sun, Anton Orekhov, Thomas N. G. Meier, Johannes Knolle, Christian H. Back, Lin Chen
Materials Science
Low-scaling GW calculations of quasi-particle energies for extended systems within the numerical atomic orbital framework
Min-Ye Zhang, Peize Lin, Rong Shi et al. (+1 more)
The many-body perturbation theory within the $GW$ approximation is a widely used method for describing the electronic band structures in real materials. Its application to large-scale systems is, however, impeded by its high computational cost. The rate-limiting steps in a typical $GW$ implementation are the evaluation of the polarization function under the random phase approximation (RPA) and the evaluation of the $GW$ self-energy, both of which have a canonical $O(N^4)$ scaling with $N$ being the system size. The conventional space-time
algorithm within the plane-wave basis sets reduces the scaling from $O(N^4)$ to $O(N^3)$, albeit with a large prefactor and increased
memory cost. Here, we present a space-time
algorithm within the numerical atomic orbital (NAO) basis-set framework, for which the evaluation of the polarization function and self-energy is formally reduced to $O(N^2)$ or better with respect to system size. This is achieved by computing these quantities in real space, where low-scaling
algorithms can be formulated by leveraging the localized resolution of identity (LRI) technique. The resulting NAO-based, LRI-enhanced space-time $GW$
algorithm has been implemented in the LibRPA library interfaced with the FHI-aims code package.
Benchmark calculations for crystalline solids show that the low-scaling implementation yields quasi-particle energies in close agreement with the conventional $O(N^4)$ k-space formalism previously implemented in FHI-aims. For the systems studied here, the observed overall scaling is substantially reduced relative to the canonical approach, and the low-scaling implementation becomes advantageous already for systems containing fewer than 100 atoms.
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All authors Min-Ye Zhang, Peize Lin, Rong Shi, Xinguo Ren
Soft Condensed Matter
Surfactant reorientation under shear: dynamic surface tension and droplet deformation
Alexandra J. Hardy, Abdallah Daddi-Moussa-Ider and Elsen Tjhung
Surfactants are amphiphilic molecules that are generally anisotropic rather than spherical. Their orientation is therefore governed by the interplay between shear-induced reorientation, thermal rotational
diffusion, and energetic
alignment with the interface. The relative importance of these processes is characterized by the rotational Peclet number, $Pe_r$. We show that this microscopic coupling between flow and surfactant orientation can give rise to new macroscopic interfacial phenomena, including a shear-dependent effective surface tension and non-trivial droplet deformation. To investigate this mechanism, we develop a phase-field model that incorporates both the surfactant concentration and its local average orientation (polarization field). Using perturbation theory, we derive an analytical expression for the effective surface tension, which depends not only on the surfactant concentration but also on the local shear rate. We then employ a hybrid numerical method to study the deformation of a surfactant-covered droplet under imposed shear flow. For small $Pe_r$, droplet deformation can be accurately captured by a modified Taylor and Maffettone-Minale theories. For large $Pe_r$, shear-induced reorientation strongly distorts the surfactant polarization, and the droplet deformation progressively approaches that of a pure (surfactant-free) droplet.
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Soft Condensed Matter
Bonded-particle model for magneto-elastic rods
Gabriel Alkuino, Joel T. Clemmer, Christian D. Santangelo et al. (+1 more)
We develop a bonded-particle model for magneto-elastic rods that unifies large deformations, contact, and long-range
magnetic interactions within a single discrete-element framework. The rod is discretized into orientable particles connected by co-rotational bonds that capture stretching, shearing, twisting, and bending through a symmetric decomposition of relative displacement and rotation.
Magnetic coupling is introduced at the particle level: each particle carries a dipole moment that rotates with it, enabling both external-field actuation and long-range dipole–dipole interactions without modifying the structural formulation. We implement the model in LAMMPS to take advantage of its parallel efficiency, long-range electrostatic solvers, and multiphysics capabilities. We validate the model on three problems spanning writhing instabilities, non-uniform
magnetic actuation, and dipole-induced mechanical hysteresis. To demonstrate multiphysics capability, we couple the model with a
lattice Boltzmann fluid solver via the immersed boundary method and simulate filaments in oscillatory channel flow and fluid pumping by magnetically actuated cilia arrays. Across all examples, the model shows good agreement with experimental, analytical, and numerical reference results.
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All authors Gabriel Alkuino, Joel T. Clemmer, Christian D. Santangelo, Teng Zhang
Materials Science
Designing dislocation-driven polar vortex networks in twisted perovskites
William Sandholt, Nicolas Gauquelin, John Mangeri et al. (+21 more)
Twisting two atomic layers produces a
geometric moire pattern, but bonding-induced interfacial reconstruction fundamentally transforms this into an ordered dislocation network - a distinction obscured in weakly-bonded van der Waals systems. Although in-plane topological
vortex nanostructures arising from twisting-induced lateral strain modulation have been linked to periodic moire patterns in freestanding perovskite layers and 2D
bilayers, their coupling to the interfacial dislocation network in twisted layers remains unresolved. Here we demonstrate that twisting freestanding SrTiO3 layers undergo interfacial reconstruction into a network of screw dislocations, accompanied by the emergence of in-plane topological
vortices. Unlike in previous reports, these
vortices are associated with the periodicity of the dislocation network rather than with
geometric moire patterns. Four-dimensional scanning transmission electron microscopy (4D-STEM) reveals long-range ordered
vortex-antivortex arrays with nearly continuous polarisation rotation. A machine-learning interatomic potential, trained on first-principles calculations, together with phase-field modelling, confirms that competing strains within the dislocation network stabilize polar
vortex-antivortex pairs and drive the emergence of an electronic superlattice with a well-defined periodicity. Our results establish twist-controlled dislocation networks as a new and versatile route to designing local polar and electronic structures in
oxide materials.
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All authors William Sandholt, Nicolas Gauquelin, John Mangeri, Edwin Dollekamp, Gyanendra Panchal, Tamazouzt Chennit, Annick De Backer, Arno Annys, Nikolas Vitaliti, Andrea Roberto Insinga, Jonas Mejlby Hansen, Rajesh Mandal, Davi R. Rodrigues, Sandra van Aert, Katja I. Wurster, Arghya Bhowmik, Ivano E. Castelli, Søren B. Simonsen, Thomas S. Jespersen, Richard D. James, Bharat Jalan, Jo Verbeeck, Juan Maria Garcia Lastra, Nini Pryds
Soft Condensed Matter
Penetration of Rigid Rods, Flexible Rods, and Granular Jets into Low-Density Granular Media
J.E. Benítez-Zamudio, S. Hidalgo-Caballero and F. Pacheco-Vázquez
The penetration of projectiles into granular materials has been mainly studied using spherical intruders. Here we explore the dynamics of rods penetrating vertically in a two-dimensional granular bed composed of expanded polystyrene spheres. The experiments were performed using rigid rods, flexible rods and vertical arrays of non-cohesive particles, and the dynamics for the three cases was compared. In contrast to the vertical penetration observed for a single spherical projectile, high speed
videos reveal that a rod rapidly deviates from its initial vertical direction due to inhomogeneities of the bed packing fraction. Then, the rod rotates due to the torque induced by the resistance force and follows a curved trajectory until be aligned horizontally at a final depth. A short rod tends to deviate faster than a longer rod due to the smaller moment of inertia. Moreover, long flexible rods always lose their vertical
alignment and experience buckling, whereas rigid rods of the same size penetrate deeper before being deviated. On the other hand, experiments and molecular dynamics simulations show that a initially vertical array of grains also loses its verticality and stops adopting a final horizontal configuration. The granular array penetrates considerably less than the rods of equivalent mass, and the stopping mechanism is based on vertical-to-horizontal momentum transfer during a collisional process of the constituting particles.
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Statistical Mechanics
Emergent Competition Between Dynamical Channels in Nonequilibrium Systems
R. A. Dumer, M. Godoy and J. F. F. Mendes
We introduce a rejection-free continuous-time kinetic Monte Carlo framework to study
stochastic systems governed by multiple concurrent dynamical mechanisms. In this approach, the relative activity of each dynamical channel emerges self-consistently from the instantaneous configuration through its transition rates. As an illustration, we investigate a driven
antiferromagnetic Ising model on a square
lattice combining conservative Katz-Lebowitz-Spohn exchanges and nonconserving Glauber single-
spin flips. We show that the coexistence of these dynamics qualitatively reshapes the nonequilibrium phase diagram in the temperature-field plane, stabilizing
antiferromagnetic order in regions where the driving field would otherwise destroy it. Near the zero-temperature limit, the phase boundary follows a power-law scaling $T\sim|E-E_c|$ with an exponent close to unity. At intermediate temperatures, the transition belongs to the two-dimensional Ising universality class, while at low temperatures it remains continuous, with the order-parameter exponent approaching zero. Our results demonstrate that allowing competing dynamical channels to coevolve with the system can fundamentally alter its critical properties, revealing collective behavior hidden in single-dynamics descriptions.
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Statistical Mechanics · Cross-listed from q-bio.PE
When can fitness epistasis be ignored in a polygenic trait at equilibrium?
Archana Devi and Kavita Jain
Although many phenotypic traits are determined by a large number of genetic variants, the behavior of allele frequencies in a polygenic trait is not completely understood. The problem is especially challenging when the quantitative trait of interest is under epistatic selection as the allele frequency at a locus is affected by those at other loci. Here, we consider a panmictic, diploid finite population evolving under stabilizing selection and symmetric mutations when the population is in linkage
equilibrium. In the stationary state, using a
diffusion theory, we calculate the marginal distribution of allele frequency, and find parameter regimes where fitness epistasis can not be ignored for an accurate description of the frequency distribution. For such parameters, the mean deviation in the phenotypic optimum and genic variance are, however, found to be well captured even when epistatic interactions are neglected. Thus, while the presence of epistasis may not be evident in phenotypic quantities, it can strongly affect the allele frequency distribution.We also find that the allele frequency distribution at a locus is unimodal if its effect size is below a threshold effect and bimodal otherwise; these results are the
stochastic analog of the deterministic ones where the stable allele frequency becomes bistable when the effect size exceeds a threshold. Our analytical results are verified against Monte Carlo simulations and numerical integration of a Langevin equation.
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Materials Science
The switching of bipolar and unipolar magnetostriction in polycrystalline ZnO film
Suman Guchhait, Saumen Chaudhuri and A. K. Das
We report the investigation of magnetostrictive property of polycrystalline ZnO film at room temperature on rotating a
magnetic field in the plane of the film from 0 deg to 90 deg by an indigenously developed optical cantilever beam magnetometer (CBM) setup. In this study, the film exhibits bipolar (tensile & compressive) and unipolar (tensile/compressive) nature of magnetostriction with the angle of rotation of in-plane
magnetic field. Moreover, we observe switching behavior of bipolar and unipolar magnetostriction as the applied field is rotated in the plane of the film. The switching of magnetostriction is attributed to the
crystal anisotropy of the material. The appearance of bipolar and unipolar magnetostriction has made the ZnO film a suitable candidate for the fabrication of sensors as well as actuators applicable in micro and nano-electronic devices.
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Statistical Mechanics
Continuum Free-Energy Computing
Trey Li
Building on nonintrinsic Landau theory, we introduce continuum free-energy computing as a new computing paradigm in which problem instances are encoded in programmable free-energy functionals and solved by intrinsic relaxational dynamics. We identify ion-patterned FeRh as a plausible physical realization through spatial control of the local phase bias, with
antiferromagnetic-
ferromagnetic interface motion providing the relaxational mechanism. We further identify two representative task classes, a minimal operating protocol, and the main physical constraints.
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Superconductivity
Distinguishing impurity-induced bound states from Majorana-like zero-energy peaks in strained CsCa2Fe4As4F2 by scanning tunneling microscopy
Mingzhe Li, Jiashuo Gong, Huaxun Li et al. (+7 more)
Iron-based
superconductors offer a versatile platform for exploring topological superconductivity and Majorana zero modes (MZMs), with experimental confirmations in Fe(Te,Se), (Li,Fe)OHFeSe and CaKFe4As4 at ambient pressure, as well as in LiFeAs under local strain. The related properties in other iron-based
superconductors still need to be explored, especially under the application of local strain. In this study, we conduct scanning tunneling microscopy/spectroscopy measurements on CsCa2Fe4As4F2
crystals under unidirectional local strain. A fully developed superconducting gap with multiple pairs of coherence peaks are observed, and the gap sizes can be significantly modulated by local strain. Spectroscopic measurements on various types of defects including the nonmagnetic Cs-site vacancies consistently reveal pair-breaking effects. These phenomena support a fully gapped multiband superconductivity scenario with sign-changing. Notably, a sharp zero-energy conductance peak (ZECP) is universally observed on a particular type of defects by using a metallic tip, resembling the MZMs observed at interstitial Fe atoms in Fe(Te,Se) [Nat. Phys. 11, 543 (2015)]. However, by using a superconducting tip to enhance energy resolution as well as by studying the ZECP
evolution as functions of
magnetic field and tunneling transmissivity, we demonstrate that the ZECP originates from nearly degenerate Yu-Shiba-Rusinov states rather than MZMs. Our study not only provides more insights into the superconducting pairing
symmetry of CsCa2Fe4As4F2, but also establishes systematic experimental methods for identifying weak
impurity state signals and discerning the physical origins of ZECPs.
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All authors Mingzhe Li, Jiashuo Gong, Huaxun Li, Jiakang Zhang, Yuanji Li, Ruotong Yin, Shiyuan Wang, Guanghan Cao, Dong-Lai Feng, Ya-Jun Yan
Superconductivity
Scanning tunneling microscopy study of helimagnetic monolayer CrBr2 on s-wave superconductor NbSe2: a topologically trivial system due to weak interfacial coupling
Yuanji Li, Ruotong Yin, Mingzhe Li et al. (+6 more)
Hybrid magnet-
superconductor heterostructures attract significant interest for their potential to host unconventional superconductivity, topological superconductivity, and Majorana physics. Transition metal dihalides (MX2, M = transition metal, X = Cl, Br, I) are compelling
magnetic candidates due to their novel
magnetic structures and possible ferroelectricity. Here, we employ low-temperature scanning tunneling microscopy/spectroscopy to investigate the interfaces fabricated by growing helimagnet candidate CrBr2 on s-wave
superconductor NbSe2. Our results reveal that the monolayer CrBr2 is insulating, the measured low-energy electronic states on it derive entirely from the NbSe2 substrate. The superconducting properties of CrBr2/NbSe2 are nearly identical to the bare NbSe2, manifested by the superconducting gap spectra and their temperature and
magnetic field dependence, as well as the spatial distribution and bound states of
magnetic vortices. Furthermore, in-gap excitations appear only at the dirty edges of CrBr2 islands and are absent from clean edges, suggesting the lack of intrinsic edge states. Taken together, these findings establish the topologically trivial nature of the helimagnetic
insulator/s-wave
superconductor system CrBr2/NbSe2, attributable to the absence of interfacial superconducting proximity and weak
magnetic coupling.
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All authors Yuanji Li, Ruotong Yin, Mingzhe Li, Shiyuan Wang, Jiashuo Gong, Ziyuan Chen, Jiakang Zhang, Dong-Lai Feng, Ya-Jun Yan
Superconductivity
Magnetic-field-tunable commensurate multi-q charge orders on UTe2 (011) surface
Yuanji Li, Ruotong Yin, Jiashuo Gong et al. (+10 more)
The heavy-
fermion superconductor UTe2 has attracted intense interest as a candidate for
spin-triplet pairing. Recent scanning tunneling microscopy (STM) studies have reported complex charge orders (COs) on its (011) surface, but their origin and relationship with superconductivity remain controversial. Here, by performing temperature-,
magnetic field-, and sample-dependent STM measurements, we identify multiple new CO wave vectors beyond those previously reported. All these CO wave vectors are strictly locked to integer multiples of 1/14 and 1/4 of the reciprocal
lattice vectors of the UTe2 (011) surface, and multiple of them coexist in real space, collectively revealing a family of field-tunable, commensurate multi-q COs. These COs exist within an energy range much larger than the superconducting energy scale, their emergence suppresses the density of states near EF, yet show negligible coupling to bulk superconductivity and
magnetic vortices. Our findings strongly disfavor the
Fermi surface nesting or primary pair-density-wave pictures, but are consistent with a surface parent
spin order.
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All authors Yuanji Li, Ruotong Yin, Jiashuo Gong, Dengpeng Yuan, Yuguang Wang, Shiyuan Wang, Mingzhe Li, Jiakang Zhang, Ziwei Xue, Zengyi Du, Shiyong Tan, Dong-Lai Feng, Ya-Jun Yan
Statistical Mechanics
Information Theoretic Signatures of Localization and Mobility Edges in Quasiperiodic Systems
Arpita Goswami
We investigate localization transitions and mobility edge phenomena in one-dimensional quasiperiodic
lattice models using an information theoretic framework based on the Tsallis
entropy of single particle eigenstates.We employ the Tsallis
entropy as a continuous, normalized functional of wavefunction amplitudes, where the entropic index $q$ provides a tunable sensitivity to different regions of the probability distribution, enhancing the contribution of localized peaks ($q>1$) or extended components ($q<1$). Building on this framework, we introduce an
entropy-gradient susceptibility defined from the energy dependence of the Tsallis
entropy, which probes variations in eigenstate structure across the spectrum. We show that this quantity clearly distinguishes global localization transitions from mobility edge physics. In the Aubry Andre model, where all eigenstates undergo a uniform transition, the
entropy varies smoothly, resulting in a broad crossover in the susceptibility. In contrast, in systems hosting mobility edges, including a quasiperiodically modulated Su Schrieffer Heeger chain and the generalized Aubry Andre model, the coexistence of localized and extended states produces sharp spectral variations, leading to a pronounced and system size independent peak. The qualitative behavior persists over a broad range of the entropic parameter $q$, with systematic variations reflecting its role as a tunable probe of spectral structure. Our results establish an information theoretic approach that leverages the continuous $q$ dependence of Tsallis
entropy to construct a derivative based measure of spectral heterogeneity, providing a complementary and physically transparent diagnostic of mobility edge phenomena beyond conventional state resolved measures.
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Soft Condensed Matter
Single-material 4D-printed shape-morphing structures via spatially patterned strain trapping
S M Asif Iqbal, Hang Zhang, Lin Yang et al. (+3 more)
A single-step, single-material 4D printing method is developed for programmable structures featuring spatially patterned strain trapping for one-way actuation. This approach enables fabrication on desktop fused filament fabrication 3D printers through a recently developed shape-
memory strain programming method, Programming via Printing (PvP), which eliminates the need for secondary post-fabrication programming. Large (up to 50%) and spatially controlled trapped tensile strain programming is achieved by PvP model design,
geometric coding, and printing parameter optimization. While contraction naturally arises from printing-induced trapped strain, expansion is introduced via architected
lattice designs with patterned strain-enabling a full range of deformation modes. These capabilities, validated at the unit-
cell level, are further integrated into larger proof-of-concept structures to demonstrate scalability and practical implementation. This strategy provides an accessible, low-cost, and easily adoptable additive manufacturing approach for diverse functional-material applications.
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All authors S M Asif Iqbal, Hang Zhang, Lin Yang, Aoyi Luo, Joseph D. Paulsen, James H. Henderson
Statistical Mechanics · Cross-listed from math.PR
On the critical fugacity of the hard-core model on regular bipartite graphs
Daniel Hadas and Ron Peled
We establish long-range order for the hard-core model on a finite, regular bipartite graph above a threshold fugacity given in terms of expansion parameters of the graph. The result applies to the $d$-dimensional hypercube graph and, more generally, to $d$-dimensional discrete
tori of fixed side length, proving long-range order at fugacities $\lambda\ge\Omega(\frac{\log d}{d})$. Furthermore, we use reflection positivity to transfer the result to the
lattice $\mathbb{Z}^{d}$, verifying the long-standing belief that its critical fugacity is of the form $d^{-1+o(1)}$ as $d\to\infty$.
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Other Condensed Matter
Bistable Fourth Sound Resonance in Superfluid $^3$He-B due to Gap Suppression
Alexander J. Shook, Daksh Malhotra, Aymar Muhikira et al. (+1 more)
Superfluidity in $^3$He exhibits many unique properties that are of interest to modern condensed matter research, including multiple superfluid phase transitions, topological defects, and exotic classes of excitations like Majorana and Weyl
fermions. Many of the most interesting theoretical proposals, which remain underexplored, are realized in highly confined geometries, where surface effects play a dominant role in the thermodynamic and hydrodynamic properties. We have developed nanofluidic resonators capable of exciting a fourth-sound acoustic mode in thin channels with a highly confined dimension ($750-1800$ nm) that is only $1-2$ orders of magnitude larger than the superfluid coherence length. When a sufficiently large drive force is applied, we observe a non-linear softening of the resonance that we interpret as due to the flow suppression of the superfluid gap. We have developed a model of the device that allows the resonance amplitude to be calibrated into a superfluid velocity, which exhibits critical behavior at particular velocities. We identify one of the observed critical velocities as being the velocity at which the gap component parallel to the flow is suppressed to zero. We compare the calibrated velocity to the prediction of a Ginzburg-Landau model, and find reasonable agreement. This measurement represents an ongoing effort to link the hydrodynamic measurements of these nanofluidic devices to theoretical predictions regarding surface gap suppression and surface-bound states.
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All authors Alexander J. Shook, Daksh Malhotra, Aymar Muhikira, John P. Davis
Materials Science · Cross-listed from cs.LG
Hierarchy-Guided Topology Latent Flow for Molecular Graph Generation
Urvi Awasthi, Alexander Arjun Lobo and Leonid Zhukov
Generating chemically valid 3D molecules is hindered by discrete bond
topology: small local bond errors can cause global failures (valence violations, disconnections, implausible rings), especially for drug-like molecules with long-range constraints. Many unconditional 3D generators emphasize coordinates and then infer bonds or rely on post-processing, leaving
topology feasibility weakly controlled. We propose Hierarchy-Guided Latent
Topology Flow (HLTF), a planner-executor model that generates bond graphs with 3D coordinates, using a latent multi-scale plan for global context and a constraint-aware sampler to suppress
topology-driven failures. On QM9, HLTF achieves 98.8% atom stability and 92.9% valid-and-unique, improving PoseBusters validity to 94.0% (+0.9 over the strongest reported baseline). On GEOM-DRUGS, HLTF attains 85.5%/85.0% validity/valid-unique-novel without post-processing and 92.2%/91.2% after standardized relaxation, within 0.9 points of the best post-processed baseline. Explicit
topology generation also reduces "false-valid" samples that pass RDKit sanitization but fail stricter checks.
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Materials Science · Cross-listed from physics.chem-ph
ADEPT-PolyGraphMT: Automated Molecular Simulation and Multi-Task Multi-Fidelity Machine Learning for Polymer Property Generation and Prediction
Sobin Alosious, Yuhan Liu, Jiaxin Xu et al. (+4 more)
The discovery of
polymers with targeted properties is challenged by the vast chemical design space and the limited availability of consistent, high-quality data across multiple properties. In this work, an integrated
polymer informatics framework is presented that combines the Automated molecular Dynamics Engine for
Polymer simulaTions (ADEPT) workflow with multi-task and multi-fidelity machine learning (PolyGraphMT).
Polymer repeat units are represented as molecular graphs and processed using a graph neural network to learn structure-property relationships. Starting from SMILES representations for monomers, ADEPT automates the construction of atomistic models and the evaluation of their properties using molecular dynamics simulations and density functional theory calculations. The simulation data are combined with curated experimental data and group contribution theory estimates to construct a unified
dataset of approximately 62,000
polymer property values spanning 28 properties. Using this
dataset, inter-property correlations are analyzed, and multi-task learning strategies are evaluated for joint property prediction. The results show that multi-task models achieve performance comparable to single-task models in data-rich regimes and exhibit superior accuracy as training data become limited. In addition, fidelity-aware training improves predictive accuracy when combining experimental and computational data sources. The trained models are further applied to large-scale property prediction for
polymers in the PolyInfo database and the PI1M virtual
polymer library, producing physically consistent property distributions across a broad chemical space. Overall, the proposed framework provides a structured approach for scalable prediction and screening of
polymer properties across multiple property types and data fidelity levels.
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All authors Sobin Alosious, Yuhan Liu, Jiaxin Xu, Gang Liu, Renzheng Zhang, Meng Jiang, Tengfei Luo
Materials Science
Channeling-in channeling-out revisited: selected area electron channeling and electron backscatter diffraction
T. Ben Britton, M. Haroon Qaiser and Ruth M. Birch
Scanning electron microscopy combined with electron backscatter diffraction (EBSD) and electron channeling provides rich crystallographic contrast, but the mutual influence of channeling-in and channeling-out is often simplified or neglected in quantitative analyses. In this work, we use selected-area electron channeling patterns (SA-ECPs) acquired from a single-
crystal silicon wafer while recording an EBSD pattern at every incident beam direction, thereby directly probing how channeling-in affects the EBSD signal. We show that common Hough-based quality metrics (pattern quality, band contrast, and band slope), pattern-matching cross-correlation coefficients, and
Fourier-based signal-to-noise ratios all exhibit strong crystallographic modulations that follow the underlying ECP, in both raw and background-corrected patterns. Similar wide-angle channeling features are also visible in conventional, low-magnification EBSD maps, indicating that channeling-in effects are relevant under routine mapping conditions and not only in specialized ECP experiments. These observations highlight that channeling-in can significantly bias quality-based interpretation of EBSD data, with consequences for methods such as pattern blurring analysis, high-resolution strain mapping, and emerging statistical or machine-learning approaches that rely on subtle variations in diffraction patterns. The combined SA-ECP and EBSD strategy presented here offers a practical framework to visualize and potentially control channeling-in/channeling-out coupling in the SEM, suggesting new routes to design experiments and detector configurations that either mitigate or intentionally exploit these dynamical effects.
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Disordered Systems and Neural Networks
Skin-Anderson localization transitions in disordered hybrid-nonreciprocal systems
C.Wang, X. R. Wang and Hechen Ren
Anderson (localization) transition is a universal wave phenomenon characterized by a disorder-induced
quantum phase transition from extended to localized states, whereas the non-Hermitian skin effect is a generic feature of non-Hermitian systems that causes bulk states to localize at the boundaries. Here, we report an unexpected skin-Anderson localization transition arising from the interplay between these two phenomena in hybrid-nonreciprocal systems that exhibit both reciprocity and nonreciprocity in different spatial directions. In the weak-disorder regime, the states are boundary-extended, meaning they are extended in reciprocal spatial dimensions but localized at the boundaries in nonreciprocal dimensions due to the non-Hermitian skin effect. As disorder increases, these boundary-extended states transition to boundary-localized states at a critical disorder strength. Remarkably, the corresponding critical points exhibit universal characteristics akin to those of the Anderson transition in its Hermitian counterpart, including identical critical exponents within numerical errors. When disorder exceeds a higher critical threshold, a second transition occurs in which boundary-localized states become bulk-localized, thereby eliminating the non-Hermitian skin effect. Thus, the skin-Anderson localization transition establishes a new framework for controlling state localization by unifying the physics of Anderson transitions with non-Hermitian
topology.
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