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A decomposition of the exact exchange-correlation potential of time-dependent density functional theory into an interaction component and a kinetic component offers a new starting point for non- adiabatic approximations. The components are…

Chemical Physics · Physics 2018-11-14 Johanna I. Fuks , Lionel Lacombe , Soeren E. B. Nielsen , Neepa T. Maitra

A recent description of an exact map for the equilibrium structure and thermodynamics of a quantum system onto a corresponding classical system is summarized. Approximate implementations are constructed by pinning exact limits (ideal gas,…

Statistical Mechanics · Physics 2015-04-14 Jeffrey Wrighton , James Dufty , Sandipan Dutta

The Quasi-harmonic (QH) approximation uses harmonic vibrational frequencies omega(H,Q,V), computed at volumes V near the volume where the Born-Oppenheimer (BO) energy is minimum. When this is used in the harmonic free energy, QH…

Materials Science · Physics 2015-08-19 Philip B. Allen

A recently developed semiclassical approximation to exchange in one dimension is shown to be almost exact, with essentially no computational cost. The variational stability of this approximation is tested, and its far greater accuracy…

Chemical Physics · Physics 2014-08-20 Peter Elliott , Attila Cangi , Stefano Pittalis , E. K. U. Gross , Kieron Burke

Density functional theory is the workhorse of modern electronic structure calculations, with wide-ranging applications in chemistry, physics, materials science, and machine learning. At its heart lies the exchange-correlation functional, a…

Chemical Physics · Physics 2026-02-20 Fabien Tran , Susi Lehtola , Stefano Pittalis , Miguel A. L. Marques

The mathematical theory of a novel variational approximation scheme for general second and fourth order partial differential equations \begin{equation}\label{eq: A} \partial_t u - \nabla\cdot\Big(u\nabla\frac{\delta\phi}{\delta…

Analysis of PDEs · Mathematics 2023-10-19 Florentine Fleißner

In the search for an accurate and computationally efficient approximation to the exact exchange potential of Kohn-Sham density functional theory, we recently compared various semilocal exchange potentials to the exact one [F. Tran et al.,…

Strongly Correlated Electrons · Physics 2016-10-21 Fabien Tran , Peter Blaha , Markus Betzinger , Stefan Blügel

We calculate properties like equilibrium lattice parameter, bulk modulus and monovacancy formation energy for nickel (Ni), iron (Fe) and chromium (Cr) using Kohn-Sham density functional theory (DFT). We compare relative performance of local…

Materials Science · Physics 2011-09-15 Prithwish Kumar Nandi , M. C. Valsakumar , Sharat Chandra , H. K. Sahu , C. S. Sundar

We consider a class of interacting particle systems in continuous space of non-gradient type, which are reversible with respect to Poisson point processes with constant density. For these models, a rate of convergence was recently obtained…

Probability · Mathematics 2024-01-19 Chenlin Gu , Jean-Christophe Mourrat , Maximilian Nitzschner

A novel approach for GW-based calculations of quasiparticle properties for finite systems is presented, in which the screened interaction is obtained directly from a linear response calculation of the density-density correlation function.…

Strongly Correlated Electrons · Physics 2015-05-13 George Pal , Yaroslav Pavlyukh , Hans Christian Schneider , Wolfgang Huebner

The Quasi-Elastic (QE) contribution of the nuclear inclusive electron model developed in reference \cite{GNO97} is extended to the study of electroweak Charged Current (CC) induced nuclear reactions at intermediate energies of interest for…

Nuclear Theory · Physics 2019-08-15 J. Nieves , J. E. Amaro , M. Valverde

For a class of interacting particle systems in continuous space, we show that finite-volume approximations of the bulk diffusion matrix converge at an algebraic rate. The models we consider are reversible with respect to the Poisson…

Probability · Mathematics 2021-12-07 Arianna Giunti , Chenlin Gu , Jean-Christophe Mourrat

Implicit and explicit density functionals for the exchange energy in finite two-dimensional systems are developed following the approach of Becke and Roussel [Phys. Rev. A 39, 3761 (1989)]. Excellent agreement for the exchange-hole…

Strongly Correlated Electrons · Physics 2008-05-08 S. Pittalis , E. Rasanen , N. Helbig , E. K. U. Gross

We use fully self-consistent GW calculations on diamond and silicon carbide to reparametrize the Heyd-Scuseria-Ernzerhof exact exchange density functional for use in band structure calculations of semiconductors and insulators. We show that…

Mesoscale and Nanoscale Physics · Physics 2015-08-05 V. Zólyomi , J. Kürti

A fundamental feature of the quasi-normal modes (QNMs), which describe light interaction with open (leaky) systems like nanoparticles, lies in the question of the completeness of the QNMs representation and in the divergence of their field…

Optics · Physics 2019-01-08 Mohamed Ismail Abdelrahman , Boris Gralak

We assess the performance of recent density functionals for the exchange-correlation energy of a nonmolecular solid, by applying accurate calculations with the GAUSSIAN, BAND, and VASP codes to a test set of 24 solid metals and non-metals.…

Elastic wave manipulation using large arrays of resonators is driving the need for advanced simulation and optimization methods. To address this we introduce and explore a robust framework for wave control: Quasi-normal modes (QNMs).…

FNAL has been developing multiple versions of flexible quench antennas (flex-QA), including some specially optimized for high sensitivity and/or high resolution, to characterize quench events and transients during current ramping in…

Instrumentation and Detectors · Physics 2023-05-03 Stoyan Stoynev , Joe DiMarco

We derive a general expression for the electron nonequilibrium (NE) distribution function in the context of steady state quantum transport through a two-terminal nanodevice with interaction. The central idea for the use of NE distributions…

Mesoscale and Nanoscale Physics · Physics 2014-02-26 H. Ness

Composite quantum materials are the ideal examples of multifunctional systems which simultaneously host more than one novel quantum phenomenon in physics. Here, we present a combined theoretical and experimental study to demonstrate the…