A5064658078- Fusion materials and technologies
- Machine Learning in Materials Science
- Nuclear Materials and Properties
- Ion-surface interactions and analysis
- Theoretical and Computational Physics
- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- nanoparticles nucleation surface interactions
- Microstructure and mechanical properties
- Force Microscopy Techniques and Applications
- Laser-induced spectroscopy and plasma
- Nuclear reactor physics and engineering
- Parallel Computing and Optimization Techniques
- Laser Material Processing Techniques
- Laser-Ablation Synthesis of Nanoparticles
- Molecular Junctions and Nanostructures
- Advanced Data Storage Technologies
- Advanced Materials Characterization Techniques
- Advanced materials and composites
- Electron and X-Ray Spectroscopy Techniques
- Protein Structure and Dynamics
- Advanced Physical and Chemical Molecular Interactions
- Metal and Thin Film Mechanics
- Radioactive element chemistry and processing
- Mechanical and Optical Resonators
Los Alamos National Laboratory
2016-2025
Government of the United States of America
2021-2023
University of Modena and Reggio Emilia
2023
Escuela Politécnica del Ejército
2022
Clemson University
2020
Argonne National Laboratory
2018
Xiamen University
2017
Los Alamos National Security (United States)
2017
Los Alamos Medical Center
2016
Stanford University
2016
Electronic structure calculations have been instrumental in providing many important insights into a range of physical and chemical properties various molecular solid-state systems. Their importance to fields, including materials science, sciences, computational chemistry device physics, is underscored by the large fraction available public supercomputing resources devoted these calculations. As we enter exascale era, exciting new opportunities increase simulation numbers, sizes, accuracies...
The ablation of solids under femtosecond laser pulses is studied using a two-dimensional molecular-dynamics model. simulations show that different expansion regimes develop as function the injected energy. origin these lies in changes thermodynamical relaxation path material follows when intensity increases. shape pressure waves generated result absorption pulse shown to vary from bipolar at low fluence unipolar high fluence, decrease tensile strength with temperature. By combining results...
We study the basic mechanisms leading to ablation by femtosecond laser pulses using molecular dynamics and a simple two-dimensional Lennard-Jones model. demonstrate that process involves three different as function of deposited energy. In particular, it can result from mechanical fragmentation, which does not require system cross any metastability or instability line. The relevance homogeneous nucleation vaporization for description in this regime is also established.
The atomic stick-slip behavior of a Pt tip sliding on Au(111) surface is studied with force microscopy (AFM) experiments and accelerated (i.e., reduced speed) molecular dynamics (MD) simulations. MD AFM conditions are controlled to match, as closely possible, the geometry orientation, load, temperature, compliance. We observe clear without any damage. Comparison both results thermally activated Prandtl-Tomlinson model shows that at highest speeds not in regime. At lower speeds, within...
The growth process of He bubbles in W is investigated using molecular dynamics and parallel replica for rates spanning 6 orders magnitude. Fast slow regimes are defined relative to typical diffusion hopping times interstitials around the bubble. Slow allow bubble, favoring biased bubble towards surface. In contrast, at fast do not have time diffuse leading a more isotropic increasing surface damage.
As noted in Wikipedia, skin the game refers to having ‘incurred risk by being involved achieving a goal’, where ‘ is synecdoche for person involved, and metaphor actions on field of play under discussion’. For exascale applications development US Department Energy Exascale Computing Project, nothing could be more apt, with delivering comprehensive science-based computational that effectively exploit high-performance computing technologies provide breakthrough modelling simulation data...
Rare-earth and actinide complexes are critical for a wealth of clean-energy applications. Three-dimensional (3D) structural generation prediction these organometallic systems remains challenge, limiting opportunities computational chemical discovery. Here, we introduce Architector, high-throughput in-silico synthesis code s-, p-, d-, f-block mononuclear capable capturing nearly the full diversity known experimental space. Beyond space, Architector performs design new including any chemically...
As the US Department of Energy (DOE) computing facilities began deploying petascale systems in 2008, DOE was already setting its sights on exascale. In that year, DARPA published a report feasibility reaching The authors identified several key challenges pursuit exascale including power, memory, concurrency, and resiliency. That informed DOE's strategy for With deployment Oak Ridge National Laboratory's Frontier supercomputer, we have officially entered era. this paper, discuss Frontier's...
We propose a mathematical analysis of well-known numerical approach used in molecular dynamics to efficiently sample coarse-grained description the original trajectory (in terms state-to-state dynamics). This technique is called parallel replica and has been introduced by Arthur F. Voter. The principle introduce many replicas dynamics, consider first transition event observed among all replicas. effective physical time obtained summing up times elapsed for Using implementation, speed-up...
The production of energy through nuclear fusion poses serious challenges related to the stability and performance materials in extreme conditions. In particular, constant bombardment walls reactor with high doses He ions is known lead deleterous changes their microstructures. These follow from aggregation into bubbles that can grow blister, potentially leading contamination plasma, or degradation mechanical properties. We computationally study behavior small clusters atoms W conditions...
Simulating the atomistic evolution of materials over long time scales is a longstanding challenge, especially for complex systems where distribution barrier heights very heterogeneous. Such are difficult to investigate using conventional long-time scale techniques, and fact that they tend remain trapped in small regions configuration space extended periods strongly limits physical insights gained from short simulations. We introduce novel simulation technique, Parallel Trajectory Splicing...
Tungsten is a promising plasma facing material for fusion reactors. Despite many favorable properties, helium ions incoming from the are known to dramatically affect microstructure of tungsten, leading bubble growth, blistering, and/or formation fuzz. In order develop mitigation strategies, it essential understand atomistic processes that lead and subsequent microstructural changes. this work, we use large-scale Accelerated Molecular Dynamics simulations investigate small (N = 1,2) V N He M...
Machine learning (ML) plays a growing role in the design and discovery of chemicals, aiming to reduce need perform expensive experiments simulations. ML for such applications is promising but difficult, as models must generalize vast chemical spaces from small training sets have reliable uncertainty quantification metrics identify prioritize unexplored regions. Ab initio computational chemistry intuition alike often take advantage differences between conditions, rather than their absolute...
Abstract Advances in machine learning (ML) have enabled the development of interatomic potentials that promise accuracy first principles methods and low-cost, parallel efficiency empirical potentials. However, ML-based struggle to achieve transferability, i.e., provide consistent across configurations differ from those used during training. In order realize potentials, systematic scalable approaches generate diverse training sets need be developed. This work creates a set for tungsten an...
The evolution of molecular dynamics (MD) simulations has been intimately linked to that computing hardware. For decades following the creation MD, have improved with power along three principal dimensions accuracy, atom count (spatial scale), and duration (temporal scale). Since mid-2000s, computer platforms have, however, failed provide strong scaling for as scale-out central processing unit (CPU) graphics (GPU) substantial increases spatial scale do not lead proportional in temporal scale....
The determination of the solvation free energy ions and molecules holds profound importance across a spectrum applications spanning chemistry, biology, storage, environment. Molecular dynamics simulations are powerful tools for computing this critical parameter. Nevertheless, accurate efficient calculation becomes formidable endeavor when dealing with complex systems characterized by potent Coulombic interactions sluggish ion and, consequently, slow transition various metastable states. In...
Abstract The kinetics of dislocation reactions, such as multiplication, controls the plastic deformation in crystals beyond their elastic limit, therefore critical mechanisms a number applications materials science. We present series large-scale molecular dynamics simulations that shows one type nucleation at free surfaces, exhibit unconventional kinetics, including unexpectedly large rates under compression, very strong entropic stabilization tension, well non-Arrhenius behavior. These...