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Usually the ions of a particular element in solids are in positive or negative oxidation states, depending upon the chemical environment. It is highly unusual for an atom having both positive as well as negative oxidation states…

Materials Science · Physics 2021-04-19 S Kiruthika , P Ravindran

Generally hydrogen will adopt the +1, 0 or -1 oxidation state in solids depending upon the chemical environment it occupy. Typically, there are some exceptional cases in which hydrogen exhibits both anionic and cationic behavior in the same…

Materials Science · Physics 2018-08-10 S Kiruthika R Varunaa , P Ravindran

In order to identify potential hydrogen storage materials, worldwide attention has been focused on hydrides with high gravimetric and volumetric capacity. Hydrogen is a unique element that possess positive, negative or neutral oxidation…

Materials Science · Physics 2019-02-14 S Kiruthika , H. Fjellvag , P Ravindran

We examine the behaviour of hydrogen ions, atoms and molecules in alpha-boron using density functional calculations. Hydrogen behaves as a negative-U centre, with positive H ions preferring to sit off-center on inter-layer bonds and…

Interconnect materials with ultralow dielectric constant, and good thermal and mechanical properties are crucial for the further miniaturization of electronic devices. Recently, it has been demonstrated that ultrathin amorphous boron…

A study based on density functional theory calculations was performed for the three charge states of interstitial hydrogen in Yttria. The present calculations were carried out by employing the GGA-PBE and the HSE06 exchange-correlation…

Materials Science · Physics 2012-01-26 E. L. Silva , A. G. Marinopoulos

The discovery of effective hydrogen storage materials is fundamental for the progress of a clean energy economy. Ammonia borane ($\mathrm{H_3BNH_3}$) has attracted great interest as a promising candidate but the reaction path that leads…

Chemical Physics · Physics 2019-01-30 Valerio Rizzi , Daniela Polino , Emilia Sicilia , Nino Russo , Michele Parrinello

The ammonia dimer (NH3)2 has been investigated using high--level ab initio quantum chemistry methods and density functional theory (DFT). The structure and energetics of important isomers is obtained to unprecedented accuracy without…

Chemical Physics · Physics 2009-09-29 A. Daniel Boese , Amalendu Chandra , Jan M. L. Martin , Dominik Marx

The electronic structure and the chemical state in Am binary oxides and Am-doped UO$_2$ were studied by means of x-ray absorption spectroscopy at shallow Am core ($4d$ and $5d$) edges. In particular, the Am $5f$ states were probed and the…

Chemical Physics · Physics 2023-03-17 S. M. Butorin , D. K. Shuh

The structural, electronic, and spectroscopic properties of a high-pressure phase of methane hydrate (MH-III) are studied by first principles electronic structure calculations. A detailed analysis of the atomic positions suggests that {\it…

Materials Science · Physics 2007-05-23 Toshiaki Iitaka , Toshikazu Ebisuzaki

Aromatic compounds form an unusual kind of hydrogen bond with water and ammonia molecules, known as the $\pi$-hydrogen bond. In this work, we report ab initio path integral molecular dynamics simulations enhanced by machine-learning…

Chemical Physics · Physics 2024-03-20 Krystof Brezina , Hubert Beck , Ondrej Marsalek

We assess the partition function and ionization degree of magnetized hydrogen atoms at thermodynamic equilibrium for a wide range of field intensities, $B\approx 10^5$-$10^{12}$~G. Evaluations include fitting formulae for an arbitrary…

Solar and Stellar Astrophysics · Physics 2020-04-01 Matías Vera Rueda , René D. Rohrmann

We study the hydrogen storage properties of planar boron sheets and compare them to those of graphene. The binding of molecular hydrogen to the boron sheet (0.05 eV) is stronger than that to graphene. We find that dispersion of alkali metal…

Materials Science · Physics 2009-10-27 Süleyman Er , Gilles A. de Wijs , Geert Brocks

The recent discovery of borophene, a two-dimensional allotrope of boron, raises many questions about its structure and its chemical and physical properties. Boron has a high chemical affinity to oxygen but little is known about the…

Materials Science · Physics 2020-02-28 Florian M. Arnold , Gotthard Seifert , Jens Kunstmann

Hydrogen as a fuel can be stored safely with high volumetric density in metals. It can, however, also be detrimental to metals causing embrittlement. Understanding fundamental behavior of hydrogen at atomic scale is key to improve the…

Materials Science · Physics 2020-02-05 Sytze de Graaf , Jamo Momand , Christoph Mitterbauer , Sorin Lazar , Bart J. Kooi

In order to probe electron wave functions involved in the bonding of NH$_4$F, we have performed Compton scattering experiments in an oriented single crystal and in a powder. Ab initio calculations of the Compton profiles for NH$_4$F and…

Materials Science · Physics 2009-04-21 B. Barbiellini , Ch. Bellin , G. Loupias , T. Buslaps , A. Shukla

Ab initio random structure searching with density functional theory was used to determine the zero-temperature structures of atomic metallic hydrogen from 500 GPa to 5 TPa. Including zero point motion in the harmonic approximation, we…

Materials Science · Physics 2015-05-20 Jeffrey M. McMahon , David M. Ceperley

In this work we show, that atomic metallic hydrogen (AMH) is formed inside of sintered oxide-nickel electrodes of nickel-cadmium battery over a long period of electrochemical hydrogenation (more than five years). It was established that…

Materials Science · Physics 2013-12-25 Nikolay E. Galushkin , Nataliya N. Yazvinskaya , Dmitriy N. Galushkin

An ideal material for on-board hydrogen storage must release hydrogen at practical temperature and pressure and also regenerate efficiently under similarly gentle conditions. Therefore, thermodynamically, the hydride material must lie…

Materials Science · Physics 2015-05-18 T. A. Abtew , Bi-ching Shih , Pratibha Dev , Vincent H. Crespi , Peihong Zhang

Through density functional theory and molecular dynamics calculations, we have analysed various metal polyhydrides to understand whether hydrogen is present in its molecular or atomic form - tetrahydrides of Ba,Sr,Ra, Cs and La;…

Materials Science · Physics 2023-04-27 Miriam Marqués , Miriam Pena Alvarez , Miguel Martinez-Canales , Graeme J Ackland
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