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The Axelrod approximation is widely used in astrophysical modelling codes to evaluate electron-impact excitation effective collision strengths for forbidden transitions. Approximate methods such as this are a necessity for many heavy…

High Energy Astrophysical Phenomena · Physics 2025-09-17 Leo P. Mulholland , Steven J. Bromley , Connor P. Ballance , Stuart A. Sim , Catherine A. Ramsbottom

A great many observables seen in intermediate energy heavy ion collisions can be explained on the basis of statistical equilibrium. Calculations based on statistical equilibrium can be implemented in microcanonical ensemble (energy and…

Nuclear Theory · Physics 2009-11-10 C. B. Das , S. Das Gupta , W. G. Lynch , A. Z. Mekjian , M. B. Tsang

Understanding the dynamics of the solar chromosphere is crucial to understanding energy transport across the solar atmosphere. The chromosphere is optically thick at many wavelengths and described by non-local thermodynamic equilibrium…

Solar and Stellar Astrophysics · Physics 2019-01-30 Jeffrey W. Reep , Stephen J. Bradshaw , Nicholas A. Crump , Harry P. Warren

Nitric Oxide (NO) significantly impacts energy distribution and chemical processes in the mesosphere and lower thermosphere (MLT). During geomagnetic storms, a substantial influx of energy in the thermosphere leads to an increase in NO…

Space Physics · Physics 2024-05-31 Dayakrishna Nailwal , MV Sunil Krishna , Alok Kumar Ranjan , Jia Yue

We present extensive calculations of radiative transition rates and electron impact collision strengths for Fe II. The data sets involve 52 levels from the $3d\,^7$, $3d\,^64s$, and $3d\,^54s^2$ configurations. Computations of $A$-values…

A photoionized gas in thermal equilibrium can display a thermal instability, with 3 or more solutions in the multi-branch region of the S-shape curve giving the temperature versus the radiation-to-gas-pressure ratio. Many studies have been…

Astrophysics · Physics 2009-11-11 A. C. Goncalves , S. Collin , A. -M. Dumont , L. Chevallier

Solutions for scalable, high-performance optical control are important for the development of scaled atom-based quantum technologies. Modulation of many individual optical beams is central to the application of arbitrary gate and control…

Optically trapped atoms in arrays of optical tweezers have emerged as a powerful platform for quantum information processing given the recent demonstrations of high-fidelity quantum logic gates and on-demand reconfigurable geometry. Both in…

Quantum Physics · Physics 2024-11-01 Sivaprasad Omanakuttan , Vikas Buchemmavari , Michael J. Martin , Ivan H Deutsch

Advanced computational tools that describe the interaction of electrons with structured nanophotonic materials are crucial for theoretical predictions, specific design tasks, and the interpretation of experimental results. These tools open…

Computational Physics · Physics 2026-02-16 P. Elli Stamatopoulou , Carsten Rockstuhl

The IRON Project, initiated in 1991, aims at two main objectives, i) study the characteristics of and calculate large-scale high accuracy data for atomic radiative and collisional processes, and ii) application in solving astrophysical…

Atomic Physics · Physics 2018-01-17 Sultana N. Nahar

The quality, consistency, and information content of training data is often what determines the practical value of machine-learning models for atomistic simulations. Yet, many widely used electronic-structure databases are assembled having…

We consider three recent large-scale calculations for the radiative and electron-impact excitation data of N IV, carried out with different methods and codes. The scattering calculations employed the relativistic Dirac $R$-matrix (DARC)…

Solar and Stellar Astrophysics · Physics 2019-02-20 G. Del Zanna , L. Fernandez-Menchero , N. R. Badnell

The high-performance computing resources and the constant improvement of both numerical simulation accuracy and the experimental measurements with which they are confronted, bring a new compulsory step to strengthen the credence given to…

Computation · Statistics 2019-03-01 J-B. Blanchard , G. Damblin , J-M. Martinez , G. Arnaud , F. Gaudier

Models of stellar spectra are necessary for interpreting light from individual stars, planets, integrated stellar populations, nebulae, and the interstellar medium. We provide a comprehensive and homogeneous collection of synthetic spectra…

Solar and Stellar Astrophysics · Physics 2018-10-10 Carlos Allende Prieto , Lars Koesterke , Ivan Hubeny , Manuel A. Bautista , Paul S. Barklem , Sultana N. Nahar

Atomistic simulations provide insights into structure-property relations on an atomic size and length scale, that are complementary to the macroscopic observables that can be obtained from experiments. Quantitative predictions, however, are…

Materials Science · Physics 2021-04-14 Nataliya Lopanitsyna , Chiheb Ben Mahmoud , Michele Ceriotti

Cold gas in galaxies provides a crucial test to evaluate the realism of cosmological hydrodynamical simulations. To extract the atomic and molecular hydrogen properties of the simulated galaxy population, postprocessing methods taking the…

Machine learning interatomic potentials (MLIPs) are routinely used atomic simulations, but generating databases of atomic configurations used in fitting these models is a laborious process, requiring significant computational and human…

Materials Science · Physics 2022-07-26 Connor Allen , Albert P. Bartók

$Aims.$ We present a database of 43,340 atmospheric models ($\sim$80,000 models at the conclusion of the project) for stars with stellar masses between 9 and 120 $M_{\odot}$, covering the region of the OB main-sequence and Wolf-Rayet (W-R)…

Solar and Stellar Astrophysics · Physics 2020-11-18 J. Zsargo , C. R. Fierro-Santillan , J. Klapp , A. Arrieta , L. Arias , J. M. Valencia , L. Di G. Sigalotti , M. Hareter , R. E. Puebla

Opacities and chemical abundance data are crucial ingredients of ultracool dwarf and extrasolar giant planet atmosphere models. We report here on the detailed sources of molecular opacity data employed by our group for this application. We…

Astrophysics · Physics 2009-11-13 Richard S. Freedman , Mark S. Marley , Katharina Lodders

Global air quality forecasting grapples with extreme spatial heterogeneity and the poor generalization of existing transductive models to unseen regions. To tackle this, we propose OmniAir, a semantic topology learning framework tailored…

Machine Learning · Computer Science 2026-01-30 Zhiqing Cui , Siru Zhong , Ming Jin , Shirui Pan , Qingsong Wen , Yuxuan Liang
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