H + H<sub>2</sub>: Potential‐Energy Surfaces and Elastic and Inelastic Scattering

Truhlar, Donald G.; Wyatt, Róbert E.

doi:10.1002/9780470142554.ch3

Cited by 67 publications

(14 citation statements)

References 221 publications

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“…We have modeled the spin densities using a valencebond method. This is related to the London-Eyring-Polanyi-Sato (LEPS) [123][124][125][126] approach, which has been widely used for interaction potentials, including those of the alkali-metal triatomic molecules [127,128]. In the LEPS approach, the two doublet surfaces are [123] V…”

Section: The Fermi Contact Interactionmentioning

confidence: 99%

Complexes formed in collisions between ultracold alkali-metal diatomic molecules and atoms

Frye,

Hutson

2021

Preprint

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We explore the properties of 3-atom complexes of alkali-metal diatomic molecules with alkali-metal atoms, which may be formed in ultracold collisions. We estimate the densities of vibrational states at the energy of atom-diatom collisions, and find values ranging from 2.2 to 350 K −1 . However, this density does not account for electronic near-degeneracy or electron and nuclear spins. We consider the fine and hyperfine structure expected for such complexes. The Fermi contact interaction between electron and nuclear spins can cause spin exchange between atomic and molecular spins. It can drive inelastic collisions, with resonances of three distinct types, each with a characteristic width and peak height in the inelastic rate coefficient. Some of these resonances are broad enough to overlap and produce a background loss rate that is approximately proportional to the number of outgoing inelastic channels. Spin exchange can increase the density of states from which laser-induced loss may occur.

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Section: The Fermi Contact Interactionmentioning

confidence: 99%

Complexes formed in collisions between ultracold alkali-metal diatomic molecules and atoms

Frye,

Hutson

2021

Preprint

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“…For the interactions of "orthodox" H 2 molecules with atomic hydrogen and helium see, e.g., the Refs. [226][227][228][229].…”

Section: A Dark Energy and The Cosmological Constantmentioning

confidence: 99%

Can the zero-point energy of the quantized harmonic oscillator be lower? Possible implications for the physics of "dark energy" and "dark matter"

Kastrup

2020

Preprint

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Replacing the canonical pair q and p of the classical harmonic oscillator (HO) by the locally and symplectically equivalent pair angle ϕ and action variable I implies a qualitative change of the global topological structure of the associated phase spaces: the pair (q, p) is an element of a topologically trivial plane R 2 whereas the pair (ϕ, I > 0) ∈ S 1 × R+ is an element of a topologically nontrivial, infinitely connected, punctured plane R 2 −{0}, which has the orthochronous "Lorentz" group SO ↑ (1, 2) (or its two-fold covering, the symplectic group Sp(2, R)) as its "canonical" group. Due to its infinitely many covering groups the resulting ("symplectic") spectrum of the associated quantum Hamiltonian H = ω Î is given by { ω(n + b), n = 0, 1, . . . ; b ∈ (0.1], e.g. b = 1/s, s ∈ N and large}, in contrast to the (q, p) version, where the Hamiltonian has the "orthodox" spectrum { ω(n + 1/2)}. The deeper reason for the difference is that for the description of the periodic orbit {p = p(q)} one covering of S 1 suffices, whereas one generally needs many coverings for the time evolution ϕ(t). And this, in turn, can lead to a lowering of the zero-point energies.Several theoretical and possible experimental implications of the "symplectic" spectra of the HO are discussed: The potentially most important ones concern the vibrations of diatomic molecules in the infrared, e.g. those of molecular hydrogen H2. Those symplectic spectra of the HO may provide a simultaneous key to two outstanding astrophysical puzzles, namely the nature of dark (vacuum) energy and that of dark matter: To the former because the zero-point energy b ω of free electromagnetic wave oscillator modes can be extremely small > 0 (b ≈ exp (−35) for the measured dark energy density). And a key to the dark matter problem because the quantum zeropoint energies of the electronic Born-Oppenheimer potentials in which the two nuclei of H2 or the nuclei of other primordial diatomic molecules vibrate can be lower, too, and, therefore, may lead to spectrally detuned "dark" H2 molecules during the "Dark Ages" of the universe and forming WIMPs in the hypothesized sense! All results appear to be in surprisingly good agreement with the ΛCDM model of the universe.Besides laboratory experiments the search for 21-cm radio signals from the Dark Ages of the universe and other astrophysical observations can help to explore those hypothetical implications.

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“…[1] Linear, neutral H 3 is a transition state for the hydrogen atom exchange reaction, H + HÀH!HÀH + H, with a venerable history in quantum chemistry; [2] the linear transition state is~10 kcal mol À1 above H + H 2 ; the HH separation in the transition state is 0.93 . [1] Linear, neutral H 3 is a transition state for the hydrogen atom exchange reaction, H + HÀH!HÀH + H, with a venerable history in quantum chemistry; [2] the linear transition state is~10 kcal mol À1 above H + H 2 ; the HH separation in the transition state is 0.93 .…”

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confidence: 99%

“…+ is a familiar molecule, an equilateral triangle with an HÀH separation of 0.87 . [1] Linear, neutral H 3 is a transition state for the hydrogen atom exchange reaction, H + HÀH!HÀH + H, with a venerable history in quantum chemistry; [2] the linear transition state is~10 kcal mol À1 above H + H 2 ; the HH separation in the transition state is 0.93 . Neutral H 3 is also important for an understanding of the H 3 + + e À !H 3 !H 2 + H or H+ H + H dissociative recombination process.…”

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Stabilizing H₃⁻: Or Are We Stabilizing a Proton?

Grabowski

Hoffmann

2012

ChemPhysChem

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H + H₂: Potential‐Energy Surfaces and Elastic and Inelastic Scattering

Cited by 67 publications

References 221 publications

Complexes formed in collisions between ultracold alkali-metal diatomic molecules and atoms

Complexes formed in collisions between ultracold alkali-metal diatomic molecules and atoms

Can the zero-point energy of the quantized harmonic oscillator be lower? Possible implications for the physics of "dark energy" and "dark matter"

Stabilizing H₃⁻: Or Are We Stabilizing a Proton?

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H + H2: Potential‐Energy Surfaces and Elastic and Inelastic Scattering

Cited by 67 publications

References 221 publications

Complexes formed in collisions between ultracold alkali-metal diatomic molecules and atoms

Complexes formed in collisions between ultracold alkali-metal diatomic molecules and atoms

Can the zero-point energy of the quantized harmonic oscillator be lower? Possible implications for the physics of "dark energy" and "dark matter"

Stabilizing H3−: Or Are We Stabilizing a Proton?

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H + H₂: Potential‐Energy Surfaces and Elastic and Inelastic Scattering

Stabilizing H₃⁻: Or Are We Stabilizing a Proton?