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Learning together:Towards foundation models for machine learning interatomic potentials with meta-learning

npj Computational Materials 2024年第1期10卷 1654-1662页

作者： Alice E.A.Allen Nicholas Lubbers Sakib Matin Justin Smith Richard Messerly Sergei Tretiak Kipton Barros Center for Nonlinear Studies Los Alamos National LaboratoryLos AlamosNM87545USA Theoretical Division Los Alamos National LaboratoryLos AlamosNM87545USA Computer Computationaland Statistical Sciences DivisionLos Alamos National LaboratoryLos AlamosNM87545USA Nvidia Corporation Santa ClaraCA9505USA Center for Integrated Nanotechnologies Los Alamos National LaboratoryLos AlamosNM87545USA

The development of machine learning models has led to an abundance of datasets containing quantum mechanical(QM)calculations for molecular and material ***,traditional training methods for machine learning models are unable to leverage the plethora of data available as they require that each dataset be generated using the same QM *** machine learning interatomic potentials(MLIPs)as an example,we show that meta-learning techniques,a recent advancement from the machine learning community,can be used to fit multiple levels of QMtheory in the same training ***-learning changes the training procedure to learn a representation that can be easily re-trained to new tasks with small amounts of *** then demonstrate that metalearning enables simultaneously training to multiple large organic molecule *** a proof of concept,we examine the performance of aMLIP refit to a small drug-like molecule and show that pretraining potentials to multiple levels of theory with meta-learning improves *** difference in performance can be seen both in the reduced error and in the improved smoothness of the potential energy surface *** therefore show that meta-learning can utilize existing datasets with inconsistentQMlevels of theory to producemodels that are better at specializing to new *** opens new routes for creating pre-trained,foundationmodels for interatomic potentials.

关键词： learning utilize smoothness

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REVIEW OF TURBULENT MIXING MODELS

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Acta Mathematica Scientia 2009年第6期29卷 1703-1720页

作者： Baolian Cheng Los Alamos National Laboratory Los Alamos NM 87545 USA

Fluid mixing is an important phenomenon in many physical applications from supernova explosions to genetic structure formations. In this paper, we overview some theoretical and empirical dynamic mix models, which have been developed over the recent decades, in particular, the ensemble-average micro physical mix model, the multifluid interpenetration mix model, the phenomenological and hybrid turbulent mix models, the buoyancy drag mix model, the single fluid turbulence mix model, and the large eddy simulation mix model. The similarities, distinctions, and connections between these models and their applications are discussed.

关键词： hydrodynamic instabilities turbulent mixing

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High pressure suppression of plasticity due to an overabundance of shear embryo formation

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npj Computational Materials 2024年第1期10卷 1733-1738页

作者： Brenden W.Hamilton Timothy C.Germann Theoretical Division Los Alamos National LaboratoryLos AlamosNM87545USA

High pressure shear band formation is a critical phenomenon in energetic materials due to its influence on both mechanical strength and mechanochemical *** shear banding is known to occur in a variety of these materials,the governing dynamics of the mechanisms are not well defined for molecular *** conduct molecular dynamics simulations of shock wave induced shear band formation in the energetic material 1,3,5-trinitroperhydro-1,3,5-triazine(RDX)to assess shear band nucleation *** find,that at high pressures,the initial formation sites for shear bands,“embryos”,form in excess and rapidly lower deviatoric stresses prior to shear band formation and *** results in the suppression of plastic deformation.A local cluster analysis is used to quantify and contrast this mechanism with a more typical shear banding seen at lower *** results demonstrate a mechanism that is reversible in nature and that supersedes shear band formation at increased *** anticipate that these results will have a broad impact on the modeling and development of high-strain rate application materials such as those for high explosives and hypersonic systems.

关键词： mechanism dynamics plasticity

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Enabling dynamic 3D coherent diffraction imaging via adaptive latent space tuning of generative autoencoders

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npj Computational Materials 2024年第1期10卷 200-214页

作者： Alexander Scheinker Reeju Pokharel Applied Electrodynamics Los Alamos National LaboratoryBikini Atoll RdLos AlamosNM87545USA Material Science and Technology Los Alamos National LaboratoryBikini Atoll RdLos AlamosNM87545USA

Coherent diffraction imaging(CDI)is an advanced non-destructive 3D X-ray imaging technique for measuring a sample’s electron *** main challenge of CDI is loss of phase information in diffraction intensity measurements,resulting in lengthy iterative reconstruction processes that can return non-unique solutions,which pose challenges for experiments attempting to track dynamic sample evolution through multiple *** the increased brightness of fourth-generation light sources enables faster samplemeasurements and drives operando experiments with Bragg CDI,there is a growing need for faster reconstruction techniques that can keep *** have developed an adaptive generative autoencoder approach for uniquely tracking a sample’s electron density as it dynamically *** approach adaptively tunes the low-dimensional latent embedding of a generative autoencoder,enabling a computationally efficient manner to account for time-varying shifting distributions in *** proof of convergence is provided as well as numerical demonstration of sample tracking with noisy measurements.

关键词： faster dynamic proof

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A Pressure Relaxation Closure Model for One-Dimensional, Two-Material Lagrangian Hydrodynamics Based on the Riemann Problem

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Communications in Computational Physics 2010年第5期7卷 927-976页

作者： James R.Kamm Mikhail J.Shashkov Applied Physics Division Los Alamos National LaboratoryLos AlamosNM 87545USA Theoretical Division Los Alamos National LaboratoryLos AlamosNM 87545USA

Despite decades of development, Lagrangian hydrodynamics of strengthfree materials presents numerous open issues, even in one dimension. We focus on theproblem of closing a system of equations for a two-material cell under the assumptionof a single velocity model. There are several existing models and approaches, eachpossessing different levels of fidelity to the underlying physics and each exhibitingunique features in the computed solutions. We consider the case in which the changein heat in the constituent materials in the mixed cell is assumed equal. An instantaneous pressure equilibration model for a mixed cell can be cast as four equations infour unknowns, comprised of the updated values of the specific internal energy andthe specific volume for each of the two materials in the mixed cell. The unique contribution of our approach is a physics-inspired, geometry-based model in which theupdated values of the sub-cell, relaxing-toward-equilibrium constituent pressures arerelated to a local Riemann problem through an optimization principle. This approachcouples the modeling problem of assigning sub-cell pressures to the physics associated with the local, dynamic evolution. We package our approach in the frameworkof a standard predictor-corrector time integration scheme. We evaluate our model using idealized, two material problems using either ideal-gas or stiffened-gas equationsof state and compare these results to those computed with the method of Tipton andwith corresponding pure-material calculations.

关键词： Lagrangian hydrodynamics compressible flow multi-material flow pressure relaxation

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Training data selection for accuracy and transferability of interatomic potentials

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npj Computational Materials 2022年第1期8卷 1795-1803页

作者： David Montes de Oca Zapiain Mitchell A.Wood Nicholas Lubbers Carlos ZP.ereyra Aidan P.Thompson Danny Perez Sandia National Laboratories AlbuquerqueNM87185USA Computer Computationaland Statistical Sciences DivisionLos Alamos National LaboratoryLos AlamosNM87545USA Mechanical and Aerospace Engineering University of California DavisDavisCA95616USA Theoretical Division Los Alamos National LaboratoryLos AlamosNM87545USA

Advances in machine learning(ML)have enabled the development of interatomic potentials that promise the accuracy of first principles methods and the low-cost,parallel efficiency of empirical ***,ML-based potentials struggle to achieve transferability,i.e.,provide consistent accuracy across configurations that differ from those used during *** order to realize the promise of ML-based potentials,systematic and scalable approaches to generate diverse training sets need to be *** work creates a diverse training set for tungsten in an automated manner using an entropy optimization ***,multiple polynomial and neural network potentials are trained on the entropy-optimized dataset.A corresponding set of potentials are trained on an expert-curated dataset for tungsten for *** models trained to the entropy-optimized data exhibited superior transferability compared to the expert-curated ***,the models trained to the expert-curated set exhibited a significant decrease in performance when evaluated on out-of-sample configurations.

关键词： entropy transfer configuration

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Source-Independent Amplitude-Semblance Full-Waveform Inversion using a Hybrid Time-and Frequency-Domain Approach

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Communications in Computational Physics 2020年第6期28卷 328-341页

作者： Benxin Chi Lianjie Huang Geophysics Group Los Alamos National LaboratoryLos AlamosNM 87545USA

Full-waveform inversion is a promising tool to produce accurate and high-resolution subsurface *** full-waveform inversion requires an accu-rate estimation of the source wavelet,and its computational cost is *** develop a novel source-independent full-waveform inversion method using a hybrid time-and frequency-domain scheme to avoid the requirement of source wavelet estimation and to reduce the computational *** employ an amplitude-semblance objective function to not only effectively remove the source wavelet effect on full-waveform inver-sion,but also to eliminate the impact of the inconsistency of source wavelets among different shot gathers on full-waveform *** reduce the high computational cost of full-waveform inversion in the time domain,we implement our new algorithm using a hybrid time-and frequency-domain *** forward and backward wave propagation operations are conducted in the time domain,while the frequency-domain wavefields are obtained during modeling using the discrete-time Fourier *** inversion process is conducted in the frequency domain for selected *** verify our method using synthetic seismic data for the Marmousi *** results demonstrate that our novel source-independent full-waveform inversion pro-duces accurate velocity models even if the source signature is *** addition,our method can significantly reduce the computational time using the hybrid time-and frequency-domain approach compared to the conventional full-waveform inversion in the time domain.

关键词： Amplitude semblance full-waveform inversion hybrid time and frequency domain source independent source wavelet

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Micro-patterning of spintronic emitters enables ultrabroadband structured terahertz radiation

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Light(Science & Applications) 2024年第10期13卷 2000-2001页

作者： Hou-Tong Chen Center for Integrated Nanotechnologies Los Alamos National LaboratoryLos AlamosNM87545USA

Structured light beams offer promising properties for a variety of applications,but the generation of broadband structured light remains a *** opportunities are emerging in the terahertz frequency range owing to recent progress in light-driven ultrafast vectorial currents through spatially patterning spintronic and optoelectronic systems.

关键词： emitter optoelectronic enable

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Lattice Boltzmann Method for Reacting Flows in Porous Media

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Advances in Applied Mathematics and Mechanics 2010年第5期2卷 545-563页

作者： Qinjun Kang Peter C.Lichtner David R.Janecky Computational Earth Sciences Group Los Alamos National LaboratoryLos AlamosNM 87545U.S.A Ecology and Air Quality Group Los Alamos National LaboratoryLos AlamosNM 87545U.S.A

We review recent developments in lattice Boltzmann method for reacting flows in porous *** present the lattice Boltzmann approaches for incompressible flow,solute transport and chemical reactions in both the pore space and at the fluid/solid *** discuss in detail the methods to update solid phase when significant mass transfer between solids and fluids is involved due to dissolution and/or *** in different areas are presented and perspectives of applying this method to a few important fields are discussed.

关键词： Reactive flows lattice Boltzmann method porous media pore scale

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Testing of Subgrid-Scale Stress Models by Using Results from Direct Numerical Simulations

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Communications in Nonlinear Science and Numerical Simulation 1998年第2期3卷 35-40页

作者： Hongrui GONG (Health Physics Measurement, MS G761 Los Alamos National Laboratory, Los Alamos, nm 87545) Email: gong@lanl.gov Health Physics Measurement MS G761 Los Alamos National Laboratory Los Alamos NM 87545 USA

ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｔｕｒｂｕｌｅｎｔｆｌｏｗｌａｒｇｅｅｄｄｉｅｓｄｏｍｉｎａｔｅｔｈｅｐｈｙｓｉｃｓｏｆｔｈｅｆｌｏｗ．Ｍｏｓｔｏｆｔｈｅｔｒａｎｓｐｏｒｔｏｆｍａｓ，ｍｏｍｅｎｔｕｍａｎｄｅｎｅｒｇｙｉ... 详细信息

ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｔｕｒｂｕｌｅｎｔｆｌｏｗｌａｒｇｅｅｄｄｉｅｓｄｏｍｉｎａｔｅｔｈｅｐｈｙｓｉｃｓｏｆｔｈｅｆｌｏｗ．Ｍｏｓｔｏｆｔｈｅｔｒａｎｓｐｏｒｔｏｆｍａｓ，ｍｏｍｅｎｔｕｍａｎｄｅｎｅｒｇｙｉｓｄｕｅｔｏｔｈｅｌａｒｇｅｅｄｄ...

关键词： Subgridmodel Large Eddy Simulation

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