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We apply standard, first-principles calculations to a complete treatment of lattice dynamics in the harmonic approximation. The algorithm makes use of the straightforward ``frozen-phonon'' approach to the calculation of vibrational spectra…

Materials Science · Physics 2007-05-23 Hadley M. Lawler , Eric K. Chang , Eric L. Shirley

The primary purpose of the collective Thomson scattering (CTS) diagnostic at ITER is to measure the properties of fast-ion populations, in particular those of fusion-born $\alpha$-particles. Based on the present design of the diagnostic, we…

We demonstrate an efficient and accurate, general-purpose first-principles blueprint for calculating anharmonic vibrational free energy and predicting structural phase transition temperatures of solids. Thermodynamic integration is…

Materials Science · Physics 2024-03-14 Junsoo Park , Zhigang Wu , John W. Lawson

Ab initio calculations and a direct method are applied to derive the phonon dispersion relations and phonon density of states for the ZrC crystal. The results are in good agreement with neutron scattering data. The force constants are…

Materials Science · Physics 2013-01-28 Paweł T. Jochym , Krzysztof Parlinski

Inelastic x-ray scattering (IXS) now a widely used technique for studying the dynamics of electrons in condensed matter. We previously posed a solution to the phase problem for IXS [P. Abbamonte, et. al., Phys. Rev. Lett. {\bf 92}, 237401…

Strongly Correlated Electrons · Physics 2013-05-29 P. Abbamonte , J. P. Reed , Y. I. Joe , Yu Gan , D. Casa

We present a theory of linear optical constants based on a single-particle density matrix and implemented in an extension of the real-space multiple scattering code FEFF. This approach avoids the need to compute wave-functions explicitly,…

Materials Science · Physics 2015-05-13 M. P. Prange , J. J. Rehr , G. Rivas , J. J. Kas , John W. Lawson

We present a systematically improvable tensor hypercontraction (THC) factorization based on interpolative separable density fitting (ISDF). We illustrate algorithmic details to achieve this within the framework of Becke's atom-centered…

Chemical Physics · Physics 2020-01-15 Joonho Lee , Lin Lin , Martin Head-Gordon

We develop a framework for on-the-fly machine learned force field (MLFF) molecular dynamics (MD) simulations of warm dense matter (WDM). In particular, we employ an MLFF scheme based on the kernel method and Bayesian linear regression, with…

Computational Physics · Physics 2024-02-22 Shashikant Kumar , Xin Jing , John E. Pask , Phanish Suryanarayana

X-ray Thomson scattering (XRTS) probes the dynamic structure factor of the system, but the measured spectrum is broadened by the combined source-and-instrument function (SIF) of the setup. In order to extract properties such as temperature…

This paper presents reconstructions of homogeneous targets from the 2D and 3D Fresnel databases by one-step imaging methods based on the computation of topological derivative and topological energy fields. The electromagnetic inverse…

Analysis of PDEs · Mathematics 2025-01-28 A. Carpio , M. Pena , M. L. Rapún

X-ray Thomson scattering (XRTS) constitutes an essential technique for diagnosing material properties under extreme conditions, such as high pressures and intense laser heating. Time-dependent density functional theory (TDDFT) is one of the…

A theoretical platform is developed for active elastic-wave sensing of (stationary and advancing) fractures along bi-material interfaces in layered composites. Damaged contact surfaces are characterized by a heterogeneous distribution of…

Numerical Analysis · Mathematics 2018-01-17 Fatemeh Pourahmadian , Irene de Teresa

Thomson scattering spectra measure the response of plasma particles to incident radiation. In warm dense matter, which is opaque to visible light, x-ray Thomson scattering (XRTS) enables a detailed probe of the electron distribution and has…

Plasma Physics · Physics 2024-08-29 Thomas W. Hentschel , Alina Kononov , Andrew D. Baczewski , Stephanie B. Hansen

We describe a novel method to compute the components of dynamo tensors from direct magnetohydrodynamic (MHD) simulations. Our method relies upon an extension and generalisation of the standard H\"ogbom CLEAN algorithm widely used in radio…

Astrophysics of Galaxies · Physics 2024-04-24 Abhijit B. Bendre , Jennifer Schober , Prasun Dhang , Kandaswamy Subramanian

We propose a generic Scattering Power Factorization Framework (SPFF) for Polarimetric Synthetic Aperture Radar (PolSAR) data to directly obtain $N$ scattering power components along with a residue power component for each pixel. Each…

Signal Processing · Electrical Eng. & Systems 2025-05-27 Debanshu Ratha , Eric Pottier , Avik Bhattacharya , Alejandro C. Frery

Coherent X-ray scattering (CXS) techniques are capable of interrogating dynamics of nano- to mesoscale materials systems at time scales spanning several orders of magnitude. However, obtaining accurate theoretical descriptions of complex…

Inferring dynamical models from low-resolution temporal data continues to be a significant challenge in biophysics, especially within transcriptomics, where separating molecular programs from noise remains an important open problem. We…

Machine Learning · Computer Science 2023-10-05 Victor Chardès , Suryanarayana Maddu , Michael J. Shelley

The dynamics and processes involved in particle-molecule scattering, including nuclear dynamics, are described and analyzed using various quantum information quantities throughout the different stages of the scattering. The main process…

Quantum Physics · Physics 2025-05-22 Martin Mendez , Federico M. Pont

The use of machine learning to estimate the energy of a group of atoms, and the forces that drive them to more stable configurations, has revolutionized the fields of computational chemistry and materials discovery. In this domain, rigorous…

Chemical Physics · Physics 2025-10-28 Filippo Bigi , Marcel Langer , Michele Ceriotti

Phononic properties are commonly studied by calculating force constants using the density functional theory (DFT) simulations. Although DFT simulations offer accurate estimations of phonon dispersion relations or thermal properties, but for…