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Ammonia is one of the most widely observed molecules in space, and many observations are able to resolve the hyperfine structure due to the electric quadrupole moment of the nitrogen nucleus. The observed spectra often display anomalies in…

Astrophysics of Galaxies · Physics 2023-09-06 J. Loreau , A. Faure , F. Lique , S. Demes , P. J. Dagdigian

Molecules with hyperfine splitting of their rotational line spectra are useful probes of optical depth, via the relative line strengths of their hyperfine components.The hyperfine splitting is particularly advantageous in interpreting the…

Astrophysics of Galaxies · Physics 2016-04-27 A. M. Mullins , R. M. Loughnane , M. P. Redman , B. Wiles , N. Guegan , J. Barrett , E. R. Keto

The temperature is a central parameter affecting the chemical and physical properties of dense cores of interstellar clouds and their evolution to star formation. The chemistry and the dust properties are temperature dependent and the…

Astrophysics of Galaxies · Physics 2015-06-03 M. Juvela , J. Harju , N. Ysard , T. Lunttila

Ammonia inversion lines are often used as probes of the physical conditions in the dense ISM. The excitation temperature between the first two para metastable (rotational) levels is an excellent probe of the gas kinetic temperature.…

Astrophysics of Galaxies · Physics 2015-05-13 Sebastien Maret , Alexandre Faure , Emanuele Scifoni , Laurent Wiesenfeld

In this work, a mass-effective temperature-surface gravity relation (MTGR) is developed for main sequence stars in the range of 6400 K < $T_{\rm eff}$ < 20000 K with log$g$ > 3.44. The MTGR allows the simple estimation of the masses of…

Solar and Stellar Astrophysics · Physics 2021-12-01 T. Kilicoglu

In this work, we consider the thermal correction to the hyperfine interaction in hydrogen, deuterium, and the $^3$He$^+$ ion. This correction is effectively described by one-loop Feynman graphs in the framework of the quantum…

Atomic Physics · Physics 2022-12-21 T. Zalialiutdinov , D. Glazov , D. Solovyev

Frequency-domain thermoreflectance (FDTR) is a widely used technique for characterizing thermal properties of multilayer thin films. However, extracting multiple parameters from FDTR measurements presents a nonlinear inverse problem due to…

Neural and Evolutionary Computing · Computer Science 2025-12-02 Bingjia Xiao , Tao Chen , Wenbin Zhang , Xin Qian , Puqing Jiang

In this article we wish to present a new method to obtain spectral functions at finite temperature and density from the Functional Renormalization Group (FRG). The FRG offers a powerful non-perturbative tool to deal with phase transitions…

High Energy Physics - Phenomenology · Physics 2014-09-17 Jochen Wambach , Ralf-Arno Tripolt , Nils Strodthoff , Lorenz von Smekal

The pseudofermion functional renormalization group (pffRG) is a computational method for determining zero-temperature phase diagrams of frustrated quantum magnets. In a recent methodological advance, the commonly employed Katanin truncation…

Strongly Correlated Electrons · Physics 2022-07-04 Marc K. Ritter , Dominik Kiese , Tobias Müller , Fabian B. Kugler , Ronny Thomale , Simon Trebst , Jan von Delft

We use our recently developed functional renormalization group (FRG) approach for quantum spin systems to investigate the phase diagram of the frustrated $J_{1}J_{2}J_{3}$ quantum Heisenberg model on a cubic lattice. From a simple…

Strongly Correlated Electrons · Physics 2023-02-28 Dmytro Tarasevych , Andreas Rückriegel , Savio Keupert , Vasilios Mitsiioannou , Peter Kopietz

This paper provides a study and discussion of earlier as well as novel more efficient schemes for the precise evaluation of finite-temperature response functions of strongly correlated quantum systems in the framework of the time-dependent…

Quantum Physics · Physics 2013-07-19 Thomas Barthel

In this paper we discuss two approximate methods previously suggested for modeling hyperfine spectral line emission for molecules whose collisional transitions rates between hyperfine levels are unknown. Hyperfine structure is seen in the…

Astrophysics of Galaxies · Physics 2015-05-18 Eric Keto , George Rybicki

We present line lists for ammonia (NH$_{3}$) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for twelve temperatures (300 -- 1300$^{\circ}$C in 100$^{\circ}$C…

Instrumentation and Methods for Astrophysics · Physics 2015-05-28 R. J. Hargreaves , G. Li , P. F. Bernath

Significant efforts have been committed to understanding the fundamental combustion chemistry of ammonia at high-pressure and low-temperature conditions with or without blending with other fuels, as these are promising to improve ammonia…

Chemical Physics · Physics 2024-10-03 Mingrui Wang , Ruoyue Tang , Xinrui Ren , Hongqing Wu , Yuxin Dong , Ting Zhang , Song Cheng

The Density Matrix Renormalization Group (DMRG) has become a powerful numerical method that can be applied to low-dimensional strongly correlated fermionic and bosonic systems. It allows for a very precise calculation of static, dynamic and…

Strongly Correlated Electrons · Physics 2008-11-26 Karen Hallberg

We derive a novel computational scheme for functional Renormalization Group (fRG) calculations for interacting fermions on 2D lattices. The scheme is based on the exchange parametrization fRG for the two-fermion interaction, with additional…

Strongly Correlated Electrons · Physics 2017-03-08 J. Lichtenstein , D. Sánchez de la Peña , D. Rohe , E. Di Napoli , C. Honerkamp , S. A. Maier

We present a new direct spectroscopic calibration for a fast estimation of the stellar metallicity [Fe/H]. These calibrations were computed using a large sample of 451 solar-type stars for which we have precise spectroscopic parameters…

Solar and Stellar Astrophysics · Physics 2012-09-04 Sérgio G. Sousa , Nuno C. Santos , Garik Israelian

The density matrix renormalization group (DMRG) algorithm was originally designed to efficiently compute the zero temperature or ground-state properties of one dimensional strongly correlated quantum systems. The development of the…

Strongly Correlated Electrons · Physics 2016-03-09 A. Nocera , G. Alvarez

A novel, to the best of our knowledge, ultralow-temperature luminescence thermometry strategy is proposed, based on a measurement of relative intensities of hyperfine components in the spectra of Ho$^{3+}$ ions doped into a crystal. A…

Optics · Physics 2025-11-25 Marina N. Popova , Mosab Diab , Boris Z. Malkin

We present LVG and non-local radiative transfer calculations involving the rotational and hyperfine structure of the spectrum of N$_2$H$^+$ with collisional rate coefficients recently derived by us. The goal of this study is to check the…

Astrophysics · Physics 2008-11-26 F. Daniel , J. Cernicharo , M. -L. Dubernet
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