Potential Function for the Inversion of Ammonia

Swalen, J. D.; Ibers, James A.

doi:10.1063/1.1701290

Cited by 296 publications

(101 citation statements)

References 18 publications

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“…46 Because ammonia has three possible hydrogen bond donors but only one lone pair for H-bond acceptance, its arrangement in the liquid and solid phases is interesting. In the solid phase, Xray diffraction indicates that each ammonia molecule is surrounded by six nearest neighbours though asymmetrical and nonlinear hydrogen bonds and each electron pair on a nitrogen atom can accommodate three hydrogen bonds.…”

Section: Physical and Chemical Properties Of Liquid Ammonia 44mentioning

confidence: 99%

The kinetics and mechanisms of organic reactions in liquid ammonia

Atherton

Page

2010

Faraday Discuss.

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Section: Physical and Chemical Properties Of Liquid Ammonia 44mentioning

confidence: 99%

The kinetics and mechanisms of organic reactions in liquid ammonia

Atherton

Page

2010

Faraday Discuss.

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“…Finally, a larger basis set, which includes / functions on N with exponent 1.0 and d functions on H with exponent 0.99 [6 ], has been employed in the present study. The molecular geometry employed for the calculation is the experimental one with r(N-H) = 1.012 A and * HNH -106.7° [7],…”

Section: Resultsmentioning

confidence: 99%

Electric Quadrupole Moment of the ₁₄N Nucleus Determined by ab initio Cl Calculation on NH₃

1986

Zeitschrift Für Naturforschung A

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Based on the calculated electric field gradient (q) from ab initio Cl wavefunctions with large basis set (including / functions on N and d functions on H) and the experimental nuclear quadrupole coupling constant (e Q q) for nitrogen in N H 3, an improved value o f the quadrupole moment o f l4N is proposed as Q ('4N ) = 2.08 x 10~26 cm 2. The value calculated using a wavefunction near the Hartree-Fock lim it enlarged ~ 10% by the Cl treatment. IntroductionA direct determination of the electric quadrupole moment of the 14N nucleus (£H14N)) is very difficult since the electronic ground state of the nitrogen atom (4S) is almost spherically symmetrical, a slight deviation from the sphericity being only due to the spin-orbit coupling. The best available method of obtaining the (?(14N) value seems to be to compute the electric field gradient (q) in mole cules containing nitrogen, whose nuclear quadru pole coupling constants (eQq) are experimentally known. Among nitrogen-containing molecules, N H 3 is best because a very accurate experimental value obtained from the microwave study in the gaseous phase is available (e(?<7( 14N) = 4.0924 ± 0.0009 MHz) [1] and because the N H 3 molecule is small enough to obtain a very accurate molecular elec tronic wavefunction to compute the electric field gradient at the site of the nitrogen nucleus.A large number of ab initio self-consistent field (SCF) and configuration interaction (Cl) calcula tions have been made on N H 3 for this purpose, as summarized in [2], The available q values at nitrogen in N H 3 obtained from several levels of accuracy are, however, in the range from about -0 .6 to -2 .0 a.u. Most of these previous studies employ ab initio SCF wavefunctions with more or less extended basis sets.While one-electron properties such as the electric field gradient may be expected to be calculated with reasonable accuracy from the Hartree-Fock SCF wavefunction, the influence of electron corre lations on the Q value is of interest, especially since the discrepancy among various calculated values is large.As shown previously, the molecular quadrupole moment of benzene, also a one-electron property, could only be calculated very accurately from an extended Cl wavefunction [3], and the calculated value of -8.778 B which agreed excellently with the most recent experimental value (-8.69 ± 0.51 B) was at variance with the Hartree-Fock SCF value ( -9.662 B) by about 10%. Results and DiscussionIn the present study q at nitrogen in NH 3, calcu lated from ab initio Cl wavefunctions of different levels of accuracy, is reported and compared to the Hartree-Fock value. From a systematic comparison of the calculated q value an improved (?(!4N) value is proposed. The calculated q or £>(,4N) value is also at variance with the Hartree-Fock value by about 10%.The ab initio wavefunction which precedes the Cl study employs the gaussian basis set of Huzinaga M om ent o f the 14N N ucleus gaussian expansion of the hydrogen 1 s orbital with a scale factor 1.2 was similarly contracted to a (2 s) set fo...

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“…We present a general onalvsIs pair-wise potential energy functions to determine the magnitudes which parallels that of Part I. 3 …”

Section: Introductionmentioning

confidence: 99%

The transfer of atoms, ions and molecular groups in solution. Part 2.—Tunnelling between harmonic wells

Schmidt¹

1984

J. Chem. Soc., Faraday Trans. 2

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We consider the use of a harmonic-oscillator model to investigate the tunnelling of atoms, ions and molecular groups between positions of equilibrium for systems in condensed phases. The use of the oscillator model is warranted in many instances for which one has reasonably accurate information about the vibrational frequencies of atoms or molecular groups together with information about the distance over which the species transfers. Thus, the harmonicoscillator model can be used in the absence of more complete information to make estimates of the rates of various kinds of heavy-centre transfers in solution. In this paper we present a general treatment for the determination of the tunnel factors which are involved in the transfer. The work constitutes an extension of the analysis of Wall and Glockler, who used a symmetric double potential well in order to investigate the resonance doubling of the vibrational spectrum of ammonia. We consider the general problem of the tunnelling between any two vibrational states of the separate potential wells. As an example, we apply the analysis to the consideration of a simple ion transfer between two centres of solvation.

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Potential Function for the Inversion of Ammonia

Cited by 296 publications

References 18 publications

The kinetics and mechanisms of organic reactions in liquid ammonia

The kinetics and mechanisms of organic reactions in liquid ammonia

Electric Quadrupole Moment of the ₁₄N Nucleus Determined by ab initio Cl Calculation on NH₃

The transfer of atoms, ions and molecular groups in solution. Part 2.—Tunnelling between harmonic wells

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Potential Function for the Inversion of Ammonia

Cited by 296 publications

References 18 publications

The kinetics and mechanisms of organic reactions in liquid ammonia

The kinetics and mechanisms of organic reactions in liquid ammonia

Electric Quadrupole Moment of the 14N Nucleus Determined by ab initio Cl Calculation on NH3

The transfer of atoms, ions and molecular groups in solution. Part 2.—Tunnelling between harmonic wells

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Electric Quadrupole Moment of the ₁₄N Nucleus Determined by ab initio Cl Calculation on NH₃