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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Electrostatic Hellmann-Feynman theorem applied to long-range interatomic forces - The hydrogen molecule.

The use of the electrostatic Hellmann-Feynman theorem for the calculation of the leading term in the 1/R expansion of the force of interaction between two well-separated hydrogen atoms is discussed. Previous work has suggested that whereas this term is determined wholly by the first-order wavefunction when calculated by perturbation theory, the use of the Hellmann-Feynman theorem apparently requires the wavefunction through second order. It is shown how the two results may be reconciled and that the Hellmann-Feynman theorem may be reformulated in such a way that only the first-order wavefunction is required.

Steiner, E.↗
DOE OSTI2020

Benchmark calculations of electron impact electronic excitation of the hydrogen molecule

We present benchmark integrated and differential cross-sections for electron collisions with H 2 using two different theoretical approaches, namely, the R-matrix and molecular convergent close-coupling. This is similar to comparative studies conducted on electron–atom collisions for H, He and Mg. Electron impact excitation to the ${\mathrm{b}}^{3}{{\Sigma}}_{\mathrm{u}}^{+}$, ${\mathrm{a}}^{3}{{\Sigma}}_{\mathrm{g}}^{+}$, ${\mathrm{B}}^{1}{{\Sigma}}_{\mathrm{u}}^{+}$, c3Πu, ${\mathrm{E}\mathrm{F}}^{1}{{\Sigma}}_{\mathrm{g}}^{+}$, C1Πu, ${\mathrm{e}}^{3}{{\Sigma}}_{\mathrm{u}}^{+}$, ${\mathrm{h}}^{3}{{\Sigma}}_{\mathrm{g}}^{+}$, ${\mathrm{B}}^{\prime 1}{{\Sigma}}_{\mathrm{u}}^{+}$ and d3Πu excited electronic states are considered. Calculations are presented in both the fixed nuclei and adiabatic nuclei approximations, where the latter is shown only for the ${\mathrm{b}}^{3}{{\Sigma}}_{\mathrm{u}}^{+}$ state. Good agreement is found for all transitions presented. Where available, we compare with existing experimental and recommended data.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS1968

Photo-ionization of the hydrogen molecule.

H molecule photoionization, using one center wave function with polarized orbital approximation to obtain oscillator strengths in 700 to 300 angstrom range

Khare, S. P.↗
NASA NTRS1980

Detection of energetic hydrogen molecules in Jupiter's magnetosphere by Voyager 2 - Evidence for an ionospheric plasma source

The discovery of energetic (approximately 1 MeV/nuc) H3 and H2 molecules in Jupiter's magnetosphere is reported. The data, obtained with the LECP instrument on Voyager 2, showed these molecules to be present throughout the magnetosphere and as far as 180 Jupiter radii from the planet, in the 'magnetospheric wind' region. Although the relative abundances of H3 and H2 do not show a monotonic trend with distance from Jupiter, the intervals of highest abundance were found in the outer magnetosphere. As an example, in the radial range 51-56 Jupiter radii, of the dayside magnetosphere, the abundances of H3 and H2 (0.60-0.95 MeV/nuc) were about 20 and 13-25% that of He, respectively, and the He abundance was about 1-2% that of H. Since H3(+) is expected to be an important constituent of Jupiter's ionosphere, the data provide strong evidence that, in addition to Io, the ionosphere may be an important local plasma source for the Jovian energetic particles. The measurements reported may represent the first detection in nature of molecules at energies as high as 1 MeV/nucleon.

Hamilton, D. C.↗
NASA NTRS1990

A theoretical prediction of hydrogen molecule dissociation-recombination rates including an accurate treatment of internal state nonequilibrium effects

The dissociation and recombination of H2 over the temperature range 1000-5000 K are calculated in a nonempirical manner. The computation procedure involves the calculation of the state-to-state energy transfer rate coefficients, the solution of the 349 coupled equations which form the master equation, and the determination of the phenomenological rate coefficients. The nonempirical results presented here are in good agreement with experimental data at 1000 and 3000 K.

Schwenke, David W.↗
NASA NTRS1992

Radiative shocks and hydrogen molecules in pregalactic gas - The effects of postshock radiation

Previous calculations of radiative shocks in pregalactic gas are generalized and substantially improved. The hydrodynamical conservations are solved, along with the rate equations for nonequilibrium ionization, recombination, and molecule formation, and the equation of radiative transfer, for steady-state shocks in a gas of primordial compositions. This calculation self-consistently includes the effects of the diffuse postshock emission as well as a possible external radiation flux on the postshock flow and the preshock ionization levels. A previous result is confirmed that the shocked gas cools faster than it can recombine and, as a result, is able to form an H2 concentration as high as 0.003 via the formation of H(-) and H2(+) intermediaries due to the enhanced nonequilibrium ionization fraction at 10,000 K. It is shown that, as the level of the external radiation flux is increased, the formation of and cooling by H2 molecules can be inhibited and delayed. The detailed radiation spectra and ionizing photon number fluxes emergent from these shocks are presented.

Kang, Hyesung↗
NASA NTRS1995

Hydrogen Molecules in SN 1987A

The observations of CO and SiO in the infrared spectrum of SN 1987A clearly indicate that molecules can form in the debris of a supernova explosion. Since H2 is not easily observable we compute its abundance theoretically. For conditions typical of the inner (v less than 2500 km/s) envelope of SN 1987A, the fraction of H that is in molecular form rises to approx. 1% by t approx. 800 days. For t less than 500 days the formation is dominated by the gas-phase reactions H + H(+) yields H2(+) + hv; H2(+) + H yields H2 + H(+). Thereafter, the formation is dominated by the reactions H + e yields H(-) + hv; H(-) + H yields H2 + e. At early times the H(-) may absorb approx. 10%-30% of visible photons, contributing to the apparent paucity of H alpha emission. For t greater than 1000 days the abundance of H2 'freezes out' due to the slowing of all reactions. The opacity of the supernova envelope in the range 912 less than lambda less than or approx. equal to 1400 A (the upper limit depending on temperature) is dominated by resonance scattering in the Lyman and Werner bands of H2. The resulting fluorescence emission bands of H2 in the range 1150 less than lambda less than 1650 A may be observable in the UV spectra of supernovae at late times.

Culhane, Michael↗
DOE OSTI2025

A Comparison of Electronic Structure Methods for Predicting the Hydrogenation Energies of Candidate Molecules for Hydrogen Storage

The development of novel energy materials and fuels is required to expand current available energy sources. Aiming to reach this goal, there is growing interest in using molecular hydrogen as an energy carrier due to its abundance and high energy density. Liquid organic hydrogen carriers (LOHCs) are a promising route to the large-scale storage and transport of hydrogen for use in the energy economy. The search for thermodynamically viable LOHC molecules for real world use has led to a set of constraints on the dehydrogenation enthalpy and the minimum gravimetric hydrogen capacity. These constraints allow one to formulate the search for an ideal LOHC candidate molecule as an optimization problem well suited to the strengths of machine learning and artificial intelligence computational approaches. A critical barrier to a large-scale, high-throughput screening of LOHC candidate molecules is the lack of reliable training data. Computational electronic structure methods including density functional theory, coupled cluster approximations, and diffusion Monte Carlo can be used to provide training data where experimental data are either unreliable or do not exist. In this work, we use these methods to calculate the dehydrogenation energies and enthalpies of candidate LOHC molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Solution-Phase Synthesis of Platinum-Decorated Hydrogen Tungsten Bronzes for Hydrogen Atom Transfer from Oxides to Molecules

Hydrogen bronzes can be used as hydrogen donors for the broad class of reactions involving proton-coupled electron transfer (PCET). Here, in this work, we describe a method to prepare platinum-decorated hydrogen tungsten bronzes, Pt@H x WO 3 · n H 2 O with n = 0, 1, and 2, by reacting the pristine oxides at modest temperatures with a mild reducing agent, H 3 PO 2 , and H 2 PtCl 6 in an aqueous solution. We explored the tunability and kinetics of this reaction and compared it with that of archetypal gas–solid hydrogen spillover. We demonstrate that the identity of the noble metal affects the extent of bronze reduction. This suggests that the mechanism proceeds via the adsorption of a hydrogen-atom species on the noble metal. Finally, we explored the ability of the Pt-decorated hydrogen tungsten bronzes to hydrogenate a model H + /e – acceptor, 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO). The bronze phases return to their fully oxidized states along with the subsequent reduction of TEMPO to TEMPOH. Overall, this work demonstrates a solution-phase method to obtain hydrogen bronzes, which can then be used to perform hydrogen transfer reactions, providing a pathway for the use of extended transition metal oxides as stoichiometric reagents for broad classes of hydrogenation reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on CdH20C2S2(NO2)6 by Materials Project

Cd(NH)2(CNH2)2(H2)4(NO)2(H3SO4)2O2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two ac1nrvfo molecules, four hydrogen molecules, one hydrogen peroxide molecule, two methanimine molecules, two nitroxyl molecules, and one Cd(NH)2 cluster. In the Cd(NH)2 cluster, Cd2+ is bonded in a distorted linear geometry to two equivalent N+0.33- atoms. Both Cd–N bond lengths are 2.09 Å. N+0.33- is bonded in a distorted bent 120 degrees geometry to one Cd2+ and one H1+ atom. The N–H bond length is 1.04 Å. H1+ is bonded in a single-bond geometry to one N+0.33- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlH18(BrO6)3 by Materials Project

(H2)2(AlH8O7Br)2(HO2)4(H2O)4H2O2(HO2Br)2(O2)2(Br)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two hydrobromic acid molecules, two hydrogen molecules, two hydrogen peroxide molecules, two hydroxyperoxide molecules, two hypobromous acid;hydrate molecules, four water molecules, two water molecules, and two AlH8O7Br clusters. In each AlH8O7Br cluster, Al3+ is bonded in a see-saw-like geometry to four O2- atoms. There are a spread of Al–O bond distances ranging from 1.74–1.99 Å. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.66 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the eighth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.05 Å) and one longer (1.41 Å) H–O bond length. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Br5+ atom. The O–Br bond length is 1.81 Å. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Al3+ and two H1+ atoms. In the third O2- site, O2- is bonded in a single-bond geometry to one Al3+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to three H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted water-like geometry to three H1+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Al3+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Al3+ and one Br5+ atom. The O–Br bond length is 2.07 Å. Br5+ is bonded in a distorted linear geometry to two O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BH5C4(N2O)2 by Materials Project

(B)6(CN)4(H5(C2N)2)2(CNH2)4(CHNO2)4(N2H)4(H(CO)2)2H2 crystallizes in the orthorhombic Pnn2 space group. The structure is zero-dimensional and consists of six boron molecules; four carbamic acid molecules; four diazene molecules; two formalin formaldehyde molecules; two hydrogen molecules; four hydrogen cyanide molecules; four methylamine molecules; and two n,n'-dimethylethylenediamine molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KH28S4N7O16 by Materials Project

(KNH5O4)2(H2)6(NHO)2(HNO2)2(H2S)2(NH4SO)2(N2H3SO)2(NO)2(H2O)4H2O2(SO3H)2 crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one aminohydroperoxide molecule, three hydrogen molecules, one hydrogen sulfide molecule, one hydroxylamine molecule, one hydroxylamine molecule, two water molecules, one water molecule, one KNH5O4 cluster, one N2H3SO cluster, one NH4SO cluster, and one SO3H cluster. In the KNH5O4 cluster, K1+ is bonded in a 2-coordinate geometry to one H1+ and one O2- atom. The K–H bond length is 2.41 Å. The K–O bond length is 2.64 Å. N+1.57+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.20 Å) and one longer (2.12 Å) N–O bond length. There are five inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one H1+ atom. The H–H bond length is 0.75 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.64 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a distorted L-shaped geometry to one K1+ and one H1+ atom. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to one K1+ and two H1+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one N+1.57+, one H1+, and one O2- atom. The O–O bond length is 1.44 Å. In the third O2- site, O2- is bonded in a single-bond geometry to one N+1.57+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one H1+ and one O2- atom. In the N2H3SO cluster, there are two inequivalent N+1.57+ sites. In the first N+1.57+ site, N+1.57+ is bonded in a single-bond geometry to one S2- atom. The N–S bond length is 1.48 Å. In the second N+1.57+ site, N+1.57+ is bonded in a bent 120 degrees geometry to one H1+ and one S2- atom. The N–H bond length is 1.03 Å. The N–S bond length is 1.55 Å. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one S2- atom. The H–S bond length is 1.42 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N+1.57+ atom. S2- is bonded in a tetrahedral geometry to two N+1.57+, one H1+, and one O2- atom. The S–O bond length is 1.74 Å. O2- is bonded in a distorted water-like geometry to one H1+ and one S2- atom. In the NH4SO cluster, N+1.57+ is bonded in a distorted trigonal non-coplanar geometry to two H1+ and one S2- atom. Both N–H bond lengths are 1.03 Å. The N–S bond length is 1.66 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N+1.57+ atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one S2- atom. The H–S bond length is 1.35 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.57+ atom. S2- is bonded in a 3-coordinate geometry to one N+1.57+, one H1+, and one O2- atom. The S–O bond length is 1.65 Å. O2- is bonded in a distorted water-like geometry to one H1+ and one S2- atom. In the SO3H cluster, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. S2- is bonded in a water-like geometry to two O2- atoms. There is one shorter (1.51 Å) and one longer (1.75 Å) S–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one S2- and one O2- atom. The O–O bond length is 1.44 Å. In the second O2- site, O2- is bonded in a single-bond geometry to one S2- atom. In the third O2- site, O2- is bonded in a single-bond geometry to one H1+ and one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SbH5(O2F3)2 by Materials Project

H2(H3O2)2(H2O2)6(SbF4)4(F2)4 crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of four hydrofluoric acid molecules, one hydrogen molecule, two hydrogen peroxide molecules, two water molecules, one H3O2 cluster, and two SbF4 clusters. In the H3O2 cluster, there are three inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.61 Å. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.63 Å. In the third H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.26 Å) and one longer (1.30 Å) H–O bond length. There are two inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to two H atoms. In the second O site, O is bonded in a 1-coordinate geometry to two H atoms. In each SbF4 cluster, Sb is bonded in a 2-coordinate geometry to four F atoms. There are a spread of Sb–F bond distances ranging from 1.77–2.30 Å. There are four inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one Sb atom. In the second F site, F is bonded in a single-bond geometry to one Sb atom. In the third F site, F is bonded in a single-bond geometry to one Sb atom. In the fourth F site, F is bonded in a single-bond geometry to one Sb atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H6SN2 by Materials Project

NH3NH2H2(NH2)2SHS1 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four ammonia molecules, four ammonia molecules, four hydrazine;sulfane molecules, four hydrogen molecules, and four hydrogen sulfide molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgH20C4Br2(N4O3)2 by Materials Project

MgC4H4(N2O3)2(NH2)4(H2)2(H2Br)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of eight ammonia molecules, four hydrogen molecules, four molecular hydrogen;hydrobromide molecules, and two MgC4H4(N2O3)2 clusters. In each MgC4H4(N2O3)2 cluster, Mg2+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 1.97–2.23 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a 1-coordinate geometry to two N3- and one O2- atom. Both C–N bond lengths are 1.33 Å. The C–O bond length is 1.26 Å. In the second C4+ site, C4+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.17 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted single-bond geometry to one C4+ atom. In the second N3- site, N3- is bonded in a distorted single-bond geometry to one C4+ atom. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Mg2+ and one C4+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Mg2+ and one C4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+ and two H1+ atoms.

36 MATERIALS SCIENCE↗