State-specific dissociative recombination at low energy

Takagi, H.

doi:10.1088/1742-6596/4/1/021

Cited by 9 publications

(14 citation statements)

References 12 publications

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“…4(a). A similar disagreement is also pointed out more recently 41) where another relative position different from the previous two calculations is proposed. It is well established that the PIMC method is a powerful simulation tool for studies of quantum liquids and solids.…”

Section: Structure Of the 4/7 Phasesupporting

confidence: 75%

“…According to this hypothesis, the spin entropy associated with the Kagome lattice (A-sites) should be 3/4 of that for the total spins, and the system should release the remaining 1/4 entropy (B-sites) at immeasurably low temperatures (remnant entropy). As was discussed in the previous section, however, the structural assignment of the 4/7 phase is still not definitive, and the later PIMC calculations 41,45,46) suggest a very small site difference at least in terms of the wave-function distribution. Thus, the Elser's hypothesis (jJ AB j ( jJ AA j) is arguable.…”

Section: Structure Of the 4/7 Phasementioning

confidence: 92%

“…This stratificational stability due to the quantum effect is confirmed by the recent PIMC simulation. 41) On the other hand, the second layer 3 He should be compressed by overlayers even in 3 He/ 4 He/gr. It is believed that, both in the first and second layers, 10 -15% 3 He adsorbed on Grafoil is trapped in substrate heterogeneities and behaves as amorphous 3 He with a large distribution of J P giving a T-independent heat-capacity contribution.…”

Section: Density Scalementioning

confidence: 99%

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Nuclear Magnetism in Two-Dimensional Solid Helium Three on Graphite

Fukuyama

2008

J. Phys. Soc. Jpn.

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Recent studies of nuclear magnetism of monolayer helium three ( 3 He) adsorbed on graphite are reviewed. This system provides us a fascinating testing ground for physics of highly frustrated quantum spins of two dimensions (2D) such as spin liquids. Particular emphasis is devoted to the gapless spin liquid state observed in the low-density commensurate phase (4/7 phase) in the second layer. Existing experiments on heat capacity in zero magnetic field and magnetization in low fields of this phase show unambiguously the gapless excitations down to three orders of magnitude lower temperatures than the relevant exchange interactions (%1 mK). This is a new class of spin liquid, and recently electronic counterparts are found in quasi-1D and -2D conductors. On the other hand, measured magnetic properties of the incommensurate phase at much higher densities can be described as a nearly ideal 2D S ¼ 1=2 ferromagnet on a triangular lattice. We propose the existence of a new ferromagnetic commensurate phase at a density in between the 4/7 and incommensurate phases based on new heat capacity data. None of these phases show signatures of finite temperature phase transitions being consistent with the MerminWagner theorem. The exchange interactions among 3 He nuclear spins originate from atom-atom tunnel exchanges due to the large zero-point motions. Because of the steric hindrance, higher order exchanges like three-, four-, five-, and six-spin ring exchanges are expected to compete each other in similar strengths (MSE model). The applicability of the MSE model to the experimental magnetic properties of this system including its density variation is discussed. It is satisfactory except the fact that the model does not reproduce the gapless nature of the 4/7 phase, which recently stimulates different theoretical approaches such as the Hubbard model.

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Section: Structure Of the 4/7 Phasesupporting

confidence: 75%

Section: Structure Of the 4/7 Phasementioning

confidence: 92%

Section: Density Scalementioning

confidence: 99%

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Nuclear Magnetism in Two-Dimensional Solid Helium Three on Graphite

Fukuyama

2008

J. Phys. Soc. Jpn.

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“…The study of Orel et al [15] reproduced the magnitude and size of the high-energy peak, but did not accurately reproduce the shoulder on the high-energy side. Takagi [18,19] obtained good agreement for the low-energy peak, but did not reproduce all the peaks and dips in the cross section perfectly.…”

Section: Introductionmentioning

confidence: 98%

Ab initioframe-transformation calculations of direct and indirect dissociative recombination rates ofHeH++e−

Haxton

Greene

2009

Phys. Rev. A

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The HeH + cation undergoes dissociative recombination with a free electron to produce neutral He and H fragments. We present calculations using ab initio quantum defects and Fano's rovibrational frametransformation technique, employing cation rovibrational wave functions satisfying outgoing wave boundary conditions, to obtain the recombination rate in both the low-energy ͑1 -300 meV͒ and high-energy ͑ca. 0.6 hartree͒ regions. We obtain very good agreement with experimental results, demonstrating that this relatively simple method is able to reproduce observed rates for both indirect dissociative recombination, driven by rovibrationally autoionizing states in the low-energy region, and direct dissociative recombination, driven by electronically autoionizing Rydberg states attached to higher-energy excited cation channels.

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“…To see the overall feature of the DR and compare to experiments, we convolute the calculated cross section with a thermal distribution [18]. For rotational distribution, we assume the temperature of 300K.…”

Section: Dissociative Recombinationmentioning

confidence: 99%

Dissociative recombination of H⁺₂with slow electrons for a rigorous examination of theory

Takagi¹,

Hara²,

Sato³

2009

J. Phys.: Conf. Ser.

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Abstract. The Lippmann-Schwinger (LS) equation for the K matrix is numerically solved for the collision of H+ 2 + e interacting by the configuration interaction (CI), of which magnitude is carefully deduced from ab-initio calculation of electron scattering. The LS equation is extended to the negative collision energies in the context of multichannel quantum defect theory (MQDT) for the dissociative recombination (DR). Using the MQDT method for the DR, The DR cross section of H + 2 is obtained. It has turned out that the DR at low energy is induced by the indirect process with rotational excitation and the off-the-energy-shell contribution is indispensable for the accurate description. The present calculation represents the recent state specific experiment [1], and has assured the effectiveness of the MQDT method for DR.

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State-specific dissociative recombination at low energy

Cited by 9 publications

References 12 publications

Nuclear Magnetism in Two-Dimensional Solid Helium Three on Graphite

Nuclear Magnetism in Two-Dimensional Solid Helium Three on Graphite

Ab initioframe-transformation calculations of direct and indirect dissociative recombination rates ofHeH++e−

Dissociative recombination of H⁺₂with slow electrons for a rigorous examination of theory

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State-specific dissociative recombination at low energy

Cited by 9 publications

References 12 publications

Nuclear Magnetism in Two-Dimensional Solid Helium Three on Graphite

Nuclear Magnetism in Two-Dimensional Solid Helium Three on Graphite

Ab initioframe-transformation calculations of direct and indirect dissociative recombination rates ofHeH++e−

Dissociative recombination of H+2with slow electrons for a rigorous examination of theory

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Product

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Dissociative recombination of H⁺₂with slow electrons for a rigorous examination of theory