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Density functional theory (DFT) provides a theoretical framework for efficient and fairly accurate calculations of the electronic structure of molecules and crystals. The main features of density functional theory are described and DFT…

Chemical Physics · Physics 2012-06-12 Hauke Paulsen , Alfred Xaver Trautwein

Optical frequency combs (OFCs), consisting of a set of phase locked equally spaced laser frequency lines, have enabled a great leap in precision spectroscopy and metrology since seminal works of H\"ansch et al. . Nowadays, OFCs are…

Precisely modeling radio propagation in complex environments has been a significant challenge, especially with the advent of 5G and beyond networks, where managing massive antenna arrays demands more detailed information. Traditional…

Networking and Internet Architecture · Computer Science 2025-07-08 Lihao Zhang , Haijian Sun , Samuel Berweger , Camillo Gentile , Rose Qingyang Hu

Massive and luminous O-star atmospheres with winds have been studied primarily using one-dimensional (1D), spherically symmetric, and stationary models. However, observations and theory rather suggest that O-star atmospheres are highly…

Solar and Stellar Astrophysics · Physics 2024-02-02 D. Debnath , J. O. Sundqvist , N. Moens , C. Van der Sijpt , O. Verhamme , L. G. Poniatowski

Changes in the solar surface area covered by small-scale magnetic elements are thought to cause long-term changes in the solar spectral irradiance, which are important for determining the impact on Earth's climate. To study the effect of…

Solar and Stellar Astrophysics · Physics 2015-05-20 N. Afram , Y. C. Unruh , S. K. Solanki , M. Schuessler , A. Lagg , A. Voegler

We propose a Faraday anomalous dispersion optical filter (FADOF) based on a rare-earth ion doped crystal. We present theoretical analyses for the solid-state FADOF transmission. Our theoretical model predicts a maximum transmission…

Quantum Physics · Physics 2011-11-17 Wei-Bin Lin , Zong-Quan Zhou , Chuan-Feng Li , Guang-Can Guo

CONTEXT: Spectroscopic analysis remains the most common method to derive masses of massive stars, the most fundamental stellar parameter. While binary orbits and stellar pulsations can provide much sharper constraints on the stellar mass,…

Solar and Stellar Astrophysics · Physics 2015-04-29 Andreas Sander , Tomer Shenar , Rainer Hainich , Angel Gímenez-García , Helge Todt , Wolf-Rainer Hamann

The photon density operator function is used to calculate light beam propagation through turbulent atmosphere. A kinetic equation for the photon distribution function is derived and solved using the method of characteristics. Optical wave…

Quantum Physics · Physics 2009-11-13 G. P. Berman , A. A. Chumak

Distribution functions (DFs) for dynamically warm thin stellar disks residing in arbitrary axisymmetric potentials are presented which approximately reproduce pre-described surface-density and velocity-dispersion profiles. The functional…

Astrophysics · Physics 2009-10-31 Walter Dehnen

We present the Stagger-grid, a comprehensive grid of time-dependent, 3D hydrodynamic model atmospheres for late-type stars with realistic treatment of radiative transfer, covering a wide range in stellar parameters. This grid of 3D models…

Solar and Stellar Astrophysics · Physics 2015-06-15 Z. Magic , R. Collet , M. Asplund , R. Trampedach , W. Hayek , A. Chiavassa , R. F. Stein , Å. Nordlund

Accurate determination of opacity is critical for understanding radiation transport in both astrophysical and laboratory plasmas. We employ atomic data from R-Matrix calculations to investigate radiative properties in high-energy-density…

High Energy Astrophysical Phenomena · Physics 2025-10-24 Anil K. Pradhan , Sultana N. Nahar

We present an algorithm for solving the radiative transfer problem on massively parallel computers using adaptive mesh refinement and domain decomposition. The solver is based on the method of characteristics which requires an adaptive…

Astrophysics of Galaxies · Physics 2015-08-13 Lars Buntemeyer , Robi Banerjee , Thomas Peters , Mikhail Klassen , Ralph E. Pudritz

One of the largest sources of uncertainty in stellar models is caused by the treatment of convection in stellar envelopes. One dimensional stellar models often make use of the mixing length or equivalent approximations to describe…

Solar and Stellar Astrophysics · Physics 2016-05-04 Joel D. Tanner , Sarbani Basu , Pierre Demarque

We investigate the spontaneous emission of light in three-dimensional (3D) photonic crystals through theoretical calculations and simulations. It is well known that spontaneous emission depends on the radiative local density of states…

Optics · Physics 2025-10-30 Timon J. Vreman , Ad Lagendijk , Willem L. Vos

In this paper, we introduce a new 2D modulation scheme referred to as OTFS (Orthogonal Time Frequency & Space) that multiplexes information QAM symbols over new class of carrier waveforms that correspond to localized pulses in a signal…

Information Theory · Computer Science 2018-02-09 Ronny Hadani , Anton Monk

Non-LTE radiative transfer is a key tool for modern astrophysics: it is the means by which many key synthetic observables are produced, thus connecting simulations and observations. Radiative transfer models also inform our understanding of…

Solar and Stellar Astrophysics · Physics 2025-11-12 Christopher M. J. Osborne , Alexander Sannikov

In many mechanical, electrical, and general physical systems evolving over time or space, spectral analysis methods as Fast Fourier Transform (FFT), Short Term Fourier Transform (STFT), Power Spectrum Density (PSD) plays a very important…

Signal Processing · Electrical Eng. & Systems 2023-06-21 Andreas Tuor , Nico Canzani , Tobias Rüggeberg , Stefan Gorenflo , Gerd Simons , Bruno Bättig , Daniel Iseli

Molecular Dynamics (MD) simulations are a powerful tool for studying matter at the atomic scale. However, to simulate solids, an initial atomic structure is crucial for the successful execution of MD simulations, but can be difficult to…

Computational Physics · Physics 2024-11-27 Lars Dammann , Richard Kohns , Patrick Huber , Robert H. Meißner

High-mobility scenarios will be a critical part of 6G systems. Since the widely deployed orthogonal frequency division multiplexing (OFDM) waveform suffers from subcarrier orthogonality loss under severe Doppler spread, delay-Doppler domain…

Signal Processing · Electrical Eng. & Systems 2026-05-12 Yiyan Ma , Bo Ai , Jinhong Yuan , Shuangyang Li , Qingqing Cheng , Zhenguo Shi , Weijie Yuan , Zhiqiang Wei , Akram Shafie , Guoyu Ma , Yunlong Lu , Mi Yang , Zhangdui Zhong

Resonant lines are powerful probes of the interstellar and circumgalactic medium of galaxies. Their transfer in gas being a complex process, the interpretation of their observational signatures, either in absorption or in emission, is often…

Astrophysics of Galaxies · Physics 2020-04-01 Leo Michel-Dansac , Jeremy Blaizot , Thibault Garel , Anne Verhamme , Taysun Kimm , Maxime Trebitsch