Article
Physics, Fluids & Plasmas
Seher Karakuzu, Benjamin Cohen-Stead, Cristian D. Batista, Steven Johnston, Kipton Barros
Summary: In this study, a class of Hubbard-Stratonovich transformations suitable for quantum Monte Carlo simulations of Hubbard interactions is considered. A tunable parameter p allows for a continuous variation from a discrete Ising auxiliary field (p = infinity) to a compact auxiliary field that couples to electrons sinusoidally (p = 0). Testing on the single-band square and triangular Hubbard models shows that the severity of the sign problem decreases systematically with increasing p. However, selecting a finite p enables continuous sampling methods such as Langevin or Hamiltonian Monte Carlo. The tradeoffs between various simulation methods are explored through numerical benchmarks.
Article
Multidisciplinary Sciences
Zhen Zhang, Jun Ding, Evan Ma
Summary: Plastic flow in metallic glasses is not caused by identifiable local defect regions. Through a realistic model, we found that shear transformations involve only a small percentage of atoms and their locations and distribution vary under different mechanical loading conditions.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Chemistry, Physical
Alejandro Martinez-Borquez, Victor M. Trejos, Areli J. Hernandez-Guzman, Alejandro Gil-Villegas
Summary: This study presents the thermodynamic and diffusion properties of a square-well fluid using Microcanonical-Ensemble perturbation theory (MEPT). It assesses the accuracy of MEPT for modeling real substances and investigates the phase behavior of binary square-well mixtures. The results show excellent agreement between MEPT and Gibbs Ensemble Monte Carlo simulation, highlighting the relevance of higher-order perturbation terms and the potential for modeling inhomogeneous systems.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Chemistry, Physical
Suryadip Bhattacharjee, Jhumpa Adhikari
Summary: Carvacrol, a naturally occurring aromatic compound with medicinal properties, lacks comprehensive experimental VLE data, leading to the use of molecular simulation and force field techniques to predict coexistence properties at elevated temperatures. Critical state properties and acentric factor for carvacrol were determined in this study. Molecular-level investigation of the liquid phase structure and hydrogen-bonding extent was also conducted.
Article
Engineering, Chemical
Minhua Zhang, Yuankang Wang, Shuhan Liu, Yan Zhang, Yingzhe Yu
Summary: In this study, the vapor-liquid phase equilibrium data of vinyl acrylate-acetate and vinyl acrylate-vinyl acetate binary systems were calculated and fitted to simulate the separation process of vinyl acetate. The results provide a foundation for the development of the separation process.
SEPARATION AND PURIFICATION TECHNOLOGY
(2024)
Article
Chemistry, Physical
Maria M. Reif, Martin Zacharias
Summary: This study presents an approach combining alchemical modifications and physical-pathway methods to calculate absolute binding free energies. It demonstrates the successful use of simultaneous alchemical transformations and physical ligand unbinding for potential of mean force calculations and nonequilibrium pulling simulations, as well as the benefits of reducing ligand-protein interactions prior to potential of mean force calculations. These methods show promise in reducing sampling problems and improving efficiency in protein-protein binding free energy calculations.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Physics, Fluids & Plasmas
Claudio Bonati, Alessio Franchi, Andrea Pelissetto, Ettore Vicari
Summary: The study focuses on three-dimensional lattice SU(N-c) gauge theories with complex scalar fields, investigating the Higgs phases, critical behaviors, and the role of quartic scalar potential in determining symmetries. The numerical results suggest the existence of charged critical behaviors for N-f > N-f*, with 20 < N-f* < 40 in the case of N-c = 2.
Article
Chemistry, Physical
Francisco Sastre, Felipe J. Blas
Summary: In this work, two different simulation methods were used to evaluate the liquid-vapour coexistence diagram and the critical point for the square-well dimer fluid. A new algorithm based on transition rates was employed to obtain the chemical potential as a function of density near the critical point, and molecular dynamics simulations using the direct coexistence technique were conducted at low temperatures. The results were compared with the previous studies on square-well monomers and a recent proposal of a continuous version of the square-well potential.
Article
Chemistry, Physical
Victor M. Trejos, Francisco Gamez
Summary: We systematically studied the vapor-liquid equilibria of prolate Kihara fluids with dipole and quadrupole moments using Monte Carlo simulations and perturbation theory methods. The good agreement between the two approaches provides insights into the general features of molecular models with a distribution of charge modeled as a dipole plus quadrupole moments. The validation of the equation of state leads to a rapid, uncommon, and powerful instrument to expand the boundaries of perturbation theory for molecular fluids and their mixtures.
CHEMICAL PHYSICS LETTERS
(2022)
Article
Chemistry, Physical
Max Hering, Francesco Ferrari, Aleksandar Razpopov, Igor I. Mazin, Roser Valenti, Harald O. Jeschke, Johannes Reuther
Summary: We investigate the magnetism of a previously unexplored distorted spin-1/2 kagome model and uncover a rich ground state phase diagram even at the classical level. Through analytical arguments and numerical techniques, we identify different magnetic phases and predict the ground state of a newly synthesized material.
NPJ COMPUTATIONAL MATERIALS
(2022)
Article
Chemistry, Physical
Madakashira Harini, Suryadip Bhattacharjee, Jhumpa Adhikari
Summary: This study predicts the coexistence properties of thymol using theoretical methods and molecular simulations, and calculates the input of critical state properties and acentric factor through structure-property relations, providing essential data for designing efficient separation processes.
Article
Thermodynamics
W. Yang, J. Xia, X. Y. Wang, K. D. Wan, A. Megaritis, H. Zhao
Summary: This study investigates the effects of more realistic evaporation models based on non-ideal vapour-liquid equilibrium on the evaporation dynamics of multicomponent droplets and sprays. The use of the UNIFAC model for determining activity coefficients shows good agreement with measurements, and it is crucial for properly predicting evaporation processes of different compositions. The study highlights the significant impact of non-ideal vapour-liquid equilibrium models on predicting the evaporation of multi and many-component droplets and sprays, emphasizing the advantages of the UNIFAC method in such cases.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Computer Science, Software Engineering
Mohammad Sina Nabizadeh, Ravi Ramamoorthi, Albert Chern
Summary: The technique introduced in this study transforms PDE problems on infinite domains to those on bounded domains using the Kelvin Transform, resulting in continuous and compact solutions with improved efficiency and conditioning compared to traditional numerical methods. Specifically, every Poisson or Laplace equation on an infinite domain can be transformed into a corresponding equation on a compact region, and the method also applies to the Helmholtz equation.
ACM TRANSACTIONS ON GRAPHICS
(2021)
Article
Physics, Multidisciplinary
Nikita Astrakhantsev, Tom Westerhout, Apoorv Tiwari, Kenny Choo, Ao Chen, Mark H. Fischer, Giuseppe Carleo, Titus Neupert
Summary: An extensive numerical investigation was conducted to challenge the hypothesis of a spin-liquid ground state in the spin-1/2 Heisenberg model on the pyrochlore lattice. The results indicate a dimer order with broken inversion and rotational symmetry, questioning the scenario of a featureless quantum spin liquid. These findings showcase the potential of many-variable variational techniques in addressing challenging questions about three-dimensional frustrated quantum magnets.
Article
Physics, Fluids & Plasmas
S. Dujko, J. Atic, D. Bosnjakovic, R. D. White, P. Stokes, K. R. Hamilton, O. Zatsarinny, K. Bartschat, M. S. Rabasovic, D. Sevic, B. P. Marinkovic, D. Fursa, I Bray, R. P. McEachran, F. Blanco, G. Garcia, D. B. Jones, L. Campbell, M. J. Brunger
Summary: The study investigates the transport of electrons and propagation of negative ionisation fronts in indium vapour, revealing that the spatial relaxation of electrons is sensitive to the indium vapor temperature and initial conditions. The presence of indium atoms significantly affects the characteristics of the negative ionisation fronts in the vapor.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2021)
Article
Chemistry, Applied
Joshua A. Hammons, Michael H. Nielsen, Michael Bagge-Hansen, Lisa M. Lauderbach, Ralph L. Hodgin, Sorin Bastea, Laurence E. Fried, Matthew R. Cowan, Daniel A. Orlikowski, Trevor M. Willey
PROPELLANTS EXPLOSIVES PYROTECHNICS
(2020)
Editorial Material
Chemistry, Applied
Laurence E. Fried, Tommy Sewell, H. S. Udaykumar
PROPELLANTS EXPLOSIVES PYROTECHNICS
(2020)
Article
Multidisciplinary Sciences
Michael R. Armstrong, Rebecca K. Lindsey, Nir Goldman, Michael H. Nielsen, Elissaios Stavrou, Laurence E. Fried, Joseph M. Zaug, Sorin Bastea
NATURE COMMUNICATIONS
(2020)
Article
Chemistry, Physical
Cong Huy Pham, Rebecca K. Lindsey, Laurence E. Fried, Nir Goldman
JOURNAL OF CHEMICAL PHYSICS
(2020)
Article
Chemistry, Physical
Rebecca K. Lindsey, Sorin Bastea, Nir Goldman, Laurence E. Fried
Summary: This study utilizes a machine learning approach to rapidly tune density functional tight binding models for the accurate simulation of detonation chemistry in organic molecular materials. The resulting models enable simulations on ps scales and reveal the significant formation of large CxNyOz species in early shock chemistry, likely precursors to observed carbon condensates. Additionally, this approach can be used to generate quantum-based reference data for the development of full machine-learned interatomic potentials capable of simulation on even greater time and length scales.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Nir Goldman, Kyoung E. Kweon, Babak Sadigh, Tae Wook Heo, Rebecca K. Lindsey, C. Huy Pham, Laurence E. Fried, Balint Aradi, Kiel Holliday, Jason R. Jeffries, Brandon C. Wood
Summary: A rapid-screening approach has been developed for determining systematically improvable DFTB interaction potentials that can yield transferable models for a variety of conditions. The method leverages a recent reactive molecular dynamics force field and linear combinations of Chebyshev polynomials, allowing for efficient creation of multi-center representations with minimal initial DFT calculations. The workflow has been focused on TiH2 as a model system, demonstrating its ability to produce reliable DFTB models over a broad range of thermodynamic conditions.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
Joshua A. Hammons, Michael H. Nielsen, Michael Bagge-Hansen, Sorin Bastea, Chadd May, William L. Shaw, Aiden Martin, Yuelin Li, Nicholas Sinclair, Lisa M. Lauderbach, Ralph L. Hodgin, Daniel A. Orlikowski, Laurence E. Fried, Trevor M. Willey
Summary: Experimental results show that detonation nanodiamond (DND) aggregates into low fractal dimension structures within 0.1 microseconds, indicating that DND aggregation occurs on time scales comparable to particle formation. This was observed through time-resolved small-angle X-ray scattering experiments.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Matthew P. Kroonblawd, Brad A. Steele, Matthew D. Nelms, Laurence E. Fried, Ryan A. Austin
Summary: High-rate strength behavior is crucial in the shock initiation of high explosives, enhancing reactivity through plastic deformation. Molecular dynamics simulations of TATB reveal two deformation mechanisms, with compression along crystal layers activating a buckling/twinning mode and compression normal to the layers producing nanoscale shear bands. Analysis of trajectories shows that an intramolecular strain energy measure can most distinctly distinguish between these mechanisms.
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING
(2022)
Article
Chemistry, Physical
Cong Huy Pham, Rebecca K. Lindsey, Laurence E. Fried, Nir Goldman
Summary: This study improved density functional tight binding models for organic materials using a machine-learned interaction potential based on Chebyshev polynomials, achieving high-level quantum accuracy. The model exhibits transferability and extensibility through comparison to quantum chemical results, allowing for high-throughput physical and chemical predictions in computationally intractable systems.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Applied
Rebecca K. Lindsey, Cong Huy Pham, Nir Goldman, Sorin Bastea, Laurence E. Fried
Summary: This article introduces the application of the ChIMES machine learning approach in atomic-level calculations of energetic materials, providing insight into the chemistry of EM through the generation of interatomic potentials for condensed phase reacting systems.
PROPELLANTS EXPLOSIVES PYROTECHNICS
(2022)
Article
Multidisciplinary Sciences
Rebecca K. Lindsey, Nir Goldman, Laurence E. Fried, Sorin Bastea
Summary: This study employs machine-learned reactive interatomic potentials to perform large-scale simulations of nanocarbon formation from prototypical shocked C/O-containing precursor, providing direct insight into the carbon condensation process and suggesting the potential use of simulations as design tools for new nanomaterials.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Applied
Joel G. Christenson, Laurence E. Fried, Sorin Bastea, Michael H. Nielsen, Trevor M. Willey, Michael Bagge-Hansen
Summary: Thermochemical models of detonation are used to estimate energy delivery. This study proposes an equation of state (EOS) for carbon-rich condensates formed during the detonation of TATB-based explosives. The EOS shows high compressibility and exhibits graphite- and diamond-like behavior as a function of pressure. The soot model improves the accuracy of thermochemical calculations for TATB-based explosives and similar substances.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Physical
Nir Goldman, Laurence. E. E. Fried, Rebecca. K. K. Lindsey, C. Huy Pham, R. Dettori
Summary: This paper introduces the use of ChIMES to create rapidly parameterized DFTB models, which exhibit strong transferability. The authors apply this method to simulate silicon polymorphs and titanium hydride, and create a general purpose DFTB/ChIMES model for organic molecules and compounds. In all cases, DFTB/ChIMES achieves similar accuracy to the underlying quantum method with significantly reduced computational cost.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Rebecca K. Lindsey, Sorin Bastea, Yanjun Lyu, Sebastien Hamel, Nir Goldman, Laurence E. Fried
Summary: The evolution of nitrogen under shock compression up to 100 GPa is studied using molecular dynamics simulations with a machine-learned interatomic potential. The model is found to accurately reproduce the behavior of compressed liquid nitrogen, as well as experimental data, suggesting the need to revise classical models to include reversible polymerization effects.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Joel G. Christenson, Matthew P. Kroonblawd, Ryan A. Austin, Laurence E. Fried, Ronald J. Phillips