<i>Hydrogen: The Essential Element</i>

Rigden, John S.; O’Connell, James F.

doi:10.1119/1.1522705

Cited by 20 publications

(23 citation statements)

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“…Since the advent of quantum mechanics in the past century, the omnipresent hydrogen (H) atom has taken an unparalleled role in the advancement of our understanding of the physical and chemical facets of nature . Accordingly, the vast applications of hydrogen and its heavier isotopes, that is, deuterium and tritium, unequivocally reveal their “dramatic” contributions to a wide range of scientific interests from geology to medicine and from biology to cosmology .…”

Section: Introductionmentioning

confidence: 99%

How intrinsic nuclear nonadiabaticity affects molecular structure, electronic density, and conformational stability: Insights from the multicomponent DFT calculations of Mu/H isotopologues

Goli

Jalili

2018

Int J of Quantum Chemistry

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In the present work, the formalism of the multicomponent density functional theory is extended to study the open‐shell muoniated radicals of nucleic acid bases adenine, guanine, cytosine, thymine and uracil beyond the adiabatic paradigm. The derived methodology is used to characterize the stationary structures of all conceivable muoniated adducts based on the ab initio nuclear‐electronic approach, which is a mixed intermediate non‐adiabatic/adiabatic framework. The energies, geometries, atomic charges and spin‐density distributions of the muoniated species are scrutinized against their hydrogenated congeners derived within the conventional adiabatic framework. The comparative analysis of the results determines the considerable impact of nuclear quantum effects on the molecular geometry, electronic density and conformational stability while underlining the fact that the extent of the geometrical and spin‐distribution variations upon muonium substitution could be significant and mass dependent.

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Section: Introductionmentioning

confidence: 99%

How intrinsic nuclear nonadiabaticity affects molecular structure, electronic density, and conformational stability: Insights from the multicomponent DFT calculations of Mu/H isotopologues

Goli

Jalili

2018

Int J of Quantum Chemistry

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“…1 One of the alternate energy resources that are currently being pursued involves hydrogen. [2][3][4][5][6][7] Although hydrogen is among the most abundant elements on earth, exhibits the highest heating value per mass of chemical fuels, and is pollution free as water is the only by-product during combustion, there are numerous hurdles to overcome in its production, distribution, storage, and use in fuel cells. Among these, hydrogen storage is considered to be the biggest challenge in a new hydrogen economy 8 since the storage medium must meet the requirements of high gravimetric ͑ϳ10 wt % ͒ and volumetric density, fast kinetics, and favorable thermodynamics.…”

Section: Introductionmentioning

confidence: 99%

Vacancy-mediated hydrogen desorption inNaAlH4

Araújo

Ahuja

et al. 2005

Phys. Rev. B

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First-principles calculations based on density functional theory are carried out to understand the mechanisms responsible for hydrogen desorption from Ti-doped sodium-alanate ͑NaAlH 4 ͒. While the energy needed to remove a hydrogen atom from NaAlH 4 with Ti substituted either at the Na site or at Al site is found to be significantly lower than that from the pristine NaAlH 4 , the presence of Na vacancies is shown to play an even larger role: It is not only an order of magnitude smaller than that from Ti-doped sodium-alanate, but the removal of hydrogen associated with a Na vacancy is exothermic with respect to formation of H 2 molecule. Furthermore, we show that the unusual stabilization of the magic AlH 3 cluster in the vacancy containing sodium-alanate is responsible for this diminished value of the hydrogen-removal energy. It is suggested that this role of vacancies can be exploited in the design and synthesis of complex light-metal hydrides suitable for hydrogen storage.

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“…1 Special attention has been given to those materials which have Li atoms as the highly mobile entities, as for instance in Li 3 N. 2 This compound has also been discussed as a promising hydrogen storage medium [3][4][5][6][7][8][9] since it was demonstrated by Chen et al 10 that upon hydrogenation, it transforms into lithium imide ͑Li 2 NH͒ plus lithium hydride ͑LiH͒, facilitating the storage of a large amount of hydrogen in a reversible process. These findings have subsequently prompted a flurry of investigations both from experimentalists and theorists on Li 2 NH, a compound which had been known since the 1950s.…”

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confidence: 99%

Superionicity in the hydrogen storage materialLi2NH: Molecular dynamics simulations

et al. 2009

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We have employed ab initio molecular dynamics simulations in an attempt to study a temperature-induced order-disorder structural phase transformation that occurs in Li 2 NH at about 385 K. A structural phase transition was observed by us in the temperature range 300-400 K, in good agreement with experiment. This transition is associated with a melting of the cation sublattice ͑Li + ͒, giving rise to a superionic phase, which in turn is accompanied by an order-disorder transition of the N-H bond orientation. The results obtained here can contribute to a better understanding of the hydrogen storage reactions involving Li 2 NH and furthermore broaden its possible technological applications toward batteries and fuel cells.Superionic solids form a class of materials of great importance for applications in renewable energy technologies such as electrolytes in fuel cells and batteries. 1 Special attention has been given to those materials which have Li atoms as the highly mobile entities, as for instance in Li 3 N. 2 This compound has also been discussed as a promising hydrogen storage medium 3-9 since it was demonstrated by Chen et al. 10 that upon hydrogenation, it transforms into lithium imide ͑Li 2 NH͒ plus lithium hydride ͑LiH͒, facilitating the storage of a large amount of hydrogen in a reversible process. These findings have subsequently prompted a flurry of investigations both from experimentalists and theorists on Li 2 NH, a compound which had been known since the 1950s. 11 This material undergoes an order-disorder transition at around 400 K and a vivid discussion has taken place in the literature about its correct low-and high-temperature structure. [12][13][14][15][16][17][18][19] Here we intend to focus on other important questions which arise, such as: how do the ion transport properties change as Li 3 N is hydrogenated ͑i.e., in the Li 2 NH phase͒? Can the order-disorder transition in this phase enhance the ionic conductivity? What would be the mobile species in the imide compound?The high Li conductivity is expected to be significantly diminished in Li 2 NH as compared to that in Li 3 N due to strong electrostatic interaction with the partially positively charged hydrogen atoms in the NH 2− units. However, based on first-principles molecular dynamics ͑MD͒ simulations, we reveal in this work that the order-disorder transition at around 400 K actually involves the dissolution of the previously frozen Li sublattice into a superionic phase with Li + cations diffusing through channels formed by the solid NH 2− -anion sublattice. Time-averaged, such a scenario would be indistinguishable from the experimentally observed simple-cubic Li sublattice. The intriguing findings of our study may broaden the possible technological applications of Li 2 NH.In our MD simulations, forces were calculated from density-functional theory 20 as implemented in the ͑VASP͒ code. 21,22 The calculations are based on the generalized gradient approximation ͑GGA͒ ͑Ref. 23͒ and made use of the projector-augmented wave ͑PAW͒ approach. 24 A...

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Hydrogen: The Essential Element

Cited by 20 publications

References 0 publications

How intrinsic nuclear nonadiabaticity affects molecular structure, electronic density, and conformational stability: Insights from the multicomponent DFT calculations of Mu/H isotopologues

How intrinsic nuclear nonadiabaticity affects molecular structure, electronic density, and conformational stability: Insights from the multicomponent DFT calculations of Mu/H isotopologues

Vacancy-mediated hydrogen desorption inNaAlH4

Superionicity in the hydrogen storage materialLi2NH: Molecular dynamics simulations

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