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We present results predicting experimentally measurable structural quantities from molecular dynamics studies of hydrogen. In doing this, we propose a paradigm shift for experimentalists -- that the predictions from such calculations should…

Materials Science · Physics 2020-03-25 Graeme J. Ackland , John S. Loveday

We present a path-integral Monte Carlo study of dissociation in dense hydrogen ($1.75 \leq r_s \leq 2.2$, with $r_s$ the Wigner sphere radius). As temperature is lowered from $10^5$ to 5000 K, a molecular hydrogen gas forms spontaneously…

Condensed Matter · Physics 2009-10-28 W. R. Magro , D. M. Ceperley , C. Pierleoni , B. Bernu

We study the formation of first molecules, negative Hydrogen ions and molecular ions in model of the Universe with cosmological constant and cold dark matter. The cosmological recombination is described in the framework of modified model of…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-14 B. Novosyadlyj , O. Sergijenko , V. M. Shulga

Understanding the formation of molecules under conditions relevant to interstellar chemistry is fundamental to characterize the chemical evolution of the universe. Using reactive molecular dynamics simulations with model-based or…

Chemical Physics · Physics 2021-06-16 Meenu Upadhyay , Marco Pezzella , Markus Meuwly

Molecular hydrogen is the most abundant molecule in the universe. It is the first one to form and survive photo-dissociation in tenuous environments. Its formation involves catalytic reactions on the surface of interstellar grains. The…

Water (H2O) ice is an important solid constituent of many astrophysical environments. To comprehend the role of such ices in the chemistry and evolution of dense molecular clouds and comets, it is necessary to understand the freeze-out,…

The equation of state of liquid metallic hydrogen is solved numerically. Investigations are carried out at temperatures, which correspond both to the experimental conditions under which metallic hydrogen is produced on earth and the…

Chemical Physics · Physics 2016-02-25 V. T. Shvets

Here I describe recent studies of objects with molecular hydrogen emission that is strong relative to other spectral lines. Large telescopes and fast spectrometers have made the 2 {\mu}m window accessible even for relatively faint objects.…

Cosmology and Nongalactic Astrophysics · Physics 2011-07-25 Gary J. Ferland

We describe a mechanism that explains the formation of hydrocarbons and hydrocarbyls from hydrogenated graphene/graphite; hard C-C bonds are weakened and broken by the synergistic effect of chemisorbed hydrogen and high temperature…

Mesoscale and Nanoscale Physics · Physics 2014-08-22 Jose I. Martinez , Jose A. Martin-Gago , Jose Cernicharo , Pedro L. de Andres

The dissociation and subsequent ionisation of molecular material in a detached, spherically symmetric stellar wind is modelled as a star evolves from the post-asymptotic giant branch phase to a planetary nebula (i.e. from a stellar…

Astrophysics · Physics 2015-06-24 G. T. Gussie , A. R. Taylor , P. E. Dewdney , R. S. Roger

It is commonly believed that it is unfavourable for adsorbed H atoms on carbonaceous surfaces to form H$_2$ without the help of incident H atoms. Using ring-polymer instanton theory to describe multidimensional tunnelling effects, combined…

Chemical Physics · Physics 2022-04-05 Erxun Han , Wei Fang , Michail Stamatakis , Jeremy O. Richardson , Ji Chen

The importance of some atom hydrogen collisions in AGN has been investigated. The results are useful for better estimate of the hydrogen Balmer lines uxes, which usage for effective temperature diagnostics in astrophysical plasma is limited…

Astrophysics of Galaxies · Physics 2020-01-15 M. S. Dimitrijevic , V. A. Sreckovic , Lj. M. Ignjatovic , B. P. Marinkovic

Context. Radical chemical reactions on cosmic dust grains play a crucial role in forming various chemical species. Among different radicals, the hydroxyl (OH) is one of the most important ones, with a rather specific chemistry. Aims. The…

Astrophysics of Galaxies · Physics 2025-05-07 Jan Poštulka , Petr Slavíček , Johannes Kästner , Germán Molpeceres

There is accumulating evidence for the presence of complex molecules, including carbon-bearing and organic molecules, in the interstellar medium. Much of this evidence comes to us from studies of chemical composition, photo- and…

Earth and Planetary Astrophysics · Physics 2015-10-21 David W. Marshall , H. R. Sadeghpour

This paper presents an analysis of the concentration of the hydrogen molecule inside the ionized region of planetary nebulae. The equations corresponding to the ionization and chemical equilibria of H, H+, H-, H2, H2+, and H3+ are coupled…

Astrophysics · Physics 2009-11-10 I. Aleman , R. Gruenwald

$H_2$ is the most abundant interstellar species. Its deuterated forms ($HD$ and $D_2$) are also significantly abundant. Huge abundances of these molecules could be explained by considering the chemistry occurring on the interstellar dust.…

Astrophysics of Galaxies · Physics 2015-04-27 DIpen Sahu , Ankan Das , Liton Majumdar , Sandip K. Chakrabarti

The transformation of atomic hydrogen to molecular hydrogen through three-body reactions is a crucial stage in the collapse of primordial, metal-free halos, where the first generation of stars (Population III stars) in the Universe are…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Matthew J. Turk , Paul Clark , S. C. O. Glover , T. H. Greif , Tom Abel , Ralf Klessen , Volker Bromm

Hydroxylamine (NH2OH) is one of the potential precursors of complex pre-biotic species in space. Here we present a detailed experimental study of hydroxylamine formation through nitric oxide (NO) surface hydrogenation for astronomically…

Astrophysics of Galaxies · Physics 2017-05-26 Gleb Fedoseev , Sergio Ioppolo , Thanja Lamberts , Junfeng Zhen , Herma M. Cuppen , Harold Linnartz

Context. Interstellar surface chemistry is a complex process that occurs in icy layers accumulated onto grains of different sizes. Efficiency of surface processes often depends on the immediate environment of adsorbed molecules. Aims. We…

Astrophysics of Galaxies · Physics 2024-07-31 Juris Kalvāns , Aija Kalniņa , Kristaps Veitners

Methanol and its precursor formaldehyde are among the most studied organic molecules in the interstellar medium and are abundant in the gaseous and solid phases. We recently developed a model to simulate CO hydrogenation via H atoms on…

Astrophysics of Galaxies · Physics 2015-05-14 H. M. Cuppen , E. F. van Dishoeck , E. Herbst , A. G. G. M. Tielens