The vibrational structure of H+4 and D+4

Collado, José Ramón Alvarez; Aguado, Alfredo; Paniagua, Miguel

doi:10.1063/1.469303

Cited by 12 publications

(9 citation statements)

References 51 publications

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“…Below, we determine the ZPE-corrected energy profiles from ab initio calculations. For this we build on previously published ab initio work characterizing the + H 4 BO PES (Jiang et al 1989;Álvarez-Collado et al 1995;Moyano et al 2004;Alijah & Varandas 2008;Sanz-Sanz et al 2013).…”

Section: Energy Profile Of the Reaction Pathmentioning

confidence: 99%

Experimental and Theoretical Studies of the Isotope Exchange Reaction

Hillenbrand

Bowen

Liévin

et al. 2019

ApJ

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Deuterated molecules are important chemical tracers of prestellar and protostellar cores. Up to now, the titular reaction has been assumed to contribute to the generation of these deuterated molecules. We have measured the merged-beams rate coefficient for this reaction as a function of the relative collision energy in the range of about 10 meV-10 eV. By varying the internal temperature of the reacting + H 3 molecules, we found indications for the existence of a reaction barrier. We have performed detailed theoretical calculations for the zero-point-corrected energy profile of the reaction and determined a new value for the barrier height of ≈68 meV. Furthermore, we have calculated the tunneling probability through the barrier. Our experimental and theoretical results show that the reaction is essentially closed at astrochemically relevant temperatures. We derive a thermal rate coefficient of <1×10 −12 cm 3 s −1 for temperatures below 75 K with tunneling effects included and below 155 K without tunneling.

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Section: Energy Profile Of the Reaction Pathmentioning

confidence: 99%

Experimental and Theoretical Studies of the Isotope Exchange Reaction

Hillenbrand

Bowen

Liévin

et al. 2019

ApJ

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“…There are several ab initio studies of H + 4 , 4, 6-8, 38-41 however there are only two works devoted to the optimization of stable structures 40,42 and one about the optimization of stationary points. 41 Jiang and co-workers 40 found a total of 10 different stable geometrical configurations for H + 4 but a direct comparison to these calculations is not given here because the basis set and level of calculations (HF/6-311G** and QSCI/6-311G**) used in their study lower accuracy.…”

Section: A Ab Initio Calculations and Coordinatesmentioning

confidence: 99%

“…48-51, and applied to a wide variety of triatomic systems. [52][53][54] In this case, to account for the permutation invariance, the four-body terms are expressed as linear combinations of symmetry adapted functions as 42,50,51 …”

Section: Global Pes Fittingmentioning

confidence: 99%

Full dimensional potential energy surface for the ground state of $\mathbf {H_4^+}$H4+ system based on triatomic-in-molecules formalism

Sanz-Sanz¹,

Roncero²,

Paniagua³

et al. 2013

The Journal of Chemical Physics

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In this work, we present a global potential energy surface for the ground electronic state of the H + 4 based on ab initio calculations. The final fit is based on triatomics-in-molecules (TRIM) approximation and it includes extra four-body terms for the better description of some discrepancies found on the TRIM model. The TRIM method itself allows a very accurate description of the asymptotic regions. The global fit uses more than 19 000 multireference configuration interaction ab initio points. The global potential energy surface has an overall root mean square error of 0.013 eV for energies up to 2 eV above the global minimum. This work presents an analysis of the stationary points, reactant and product channels, and crossing between the two lowest TRIM adiabatic states. It is as well included a brief description of the two first excited states of the TRIM matrix, concluding that TRIM method is a very good approximation not only for the ground state but also for at least two of the excited states of H + 4 system.

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“…The basis set should be as large and flexible as possible, in order to minimize the errors due to the basis set incompleteness. We have adopted the same basis set that has been used in previous studies of the H 3 PES by Liu and Siegbahn 18 and by Boothroyd et al, 13 H 4 ϩ PES by Á lvarez-Collado et al, 23 and H 4 PES by Boothroyd et al 11 This basis set consists of nine Gaussian s-type functions optimized to describe the hydrogen atom; the six innermost are contracted, given a total of four s functions by atom; three p functions optimized in complete configuration interaction ͑CI͒ calculations on the hydrogen molecule at its equilibrium distance; and two optimized d functions to give finally the (4s,3p,2d) basis set. The total size of this basis set is of 125 atomic orbitals.…”

Section: Computational Methods and Proceduresmentioning

confidence: 99%