New Potential Energy Surface Features for the Li + HF → LiF + H Reaction

Fan, Qunchao; Li, Huidong; Feng, Hao; Sun, Weiguo; Lu, Tongxiang; Simmonett, Andrew C.; Xie, Yaoming; Schaefer, Henry F.

doi:10.1021/jp400541a

Cited by 11 publications

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References 46 publications

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“…Experimental studies [16,[19][20][21][22][23][24][25][26][27][28] focused on measurements of its reaction cross section as well as determination of product angular distributions and alignment effects. Theoretical work included extensive investigation of its potential energy surfaces (PESs) [29][30][31][32][33][34][35][36][37][38][39] and quantum dynamics calculations based on both time-dependent and time-independent methods [17,[40][41][42][43][44][45][46][47][48][49][50]. It has long served as a prototype for reactions involving an alkali metal atom and a hydrogen halide.…”

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confidence: 99%

“…It has long served as a prototype for reactions involving an alkali metal atom and a hydrogen halide. Due to the presence of three light atoms, high-level electronic structure calculations of its PESs have become possible in recent years [35][36][37][38][39]. The reaction is characterized by deep van der Waals potentials both in the incident and outgoing channels.…”

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Quantum dynamics of tunneling dominated reactions at low temperatures

Hazra

Balakrishnan

2015

New J. Phys.

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We report a quantum dynamics study of the Li + HF → LiF + H reaction at low temperatures of interest to cooling and trapping experiments. Contributions from non-zero partial waves are analyzed and results show narrow resonances in the energy dependence of the cross section that survive partial wave summation. The computations are performed using the ABC code and a simple modification of the ABC code that enables separate energy cutoffs for the reactant and product rovibrational energy levels is found to dramatically reduce the basis set size and computational expense. Results obtained using two ab initio electronic potential energy surfaces for the LiHF system show strong sensitivity to the choice of the potential. In particular, small differences in the barrier heights of the two potential surfaces are found to dramatically influence the reaction cross sections at low energies. Comparison with recent measurements of the reaction cross section (Bobbenkamp et al 2011 J. Chem. Phys. 135 204306) shows similar energy dependence in the threshold regime and an overall good agreement with experimental data compared to previous theoretical results. Also, usefulness of a recently introduced method for ultracold reactions that employ the quantum close-coupling method at shortrange and the multichannel quantum defect theory at long-range, is demonstrated in accurately evaluating product state-resolved cross sections for D + H 2 and H + D 2 reactions. offer computational advantages for reactive scattering calculations they are problematic at very low energies and have not been proven to be accurate for cold and ultracold collisions.The goal of this paper is two-fold. First, we present state-to-state reaction dynamics of the Li + HF v j ( , ) i i → LiF(v f , j f ) + H reaction using a quantum close-coupling (CC) method focusing on moderate to low collision energies in light of recent experimental data [16] that showed qualitatively different behavior at low collision energies compared to previous calculations based on a wave packet method [17]. Second, we demonstrate usefulness of a recently developed approach [18] for ultracold reactions that invoke the quantum CC method at short-range and the multichannel quantum defect theory (MQDT) at long-range. The method yields full state-resolved cross sections at comparable level of accuracy as full CC calculations but at much reduced computational expense. Results are presented for HD formation in both D + H 2 and H + D 2 reactions.The Li + HF reaction has been the topic of numerous experimental and theoretical studies over the last four decades. Experimental studies [16,[19][20][21][22][23][24][25][26][27][28] focused on measurements of its reaction cross section as well as determination of product angular distributions and alignment effects. Theoretical work included extensive investigation of its potential energy surfaces (PESs) [29][30][31][32][33][34][35][36][37][38][39] and quantum dynamics calculations based on both time-dependent and time-independent methods [17,[40][41][42]...

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Quantum dynamics of tunneling dominated reactions at low temperatures

Hazra

Balakrishnan

2015

New J. Phys.

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“…The value of 2073 cm −1 obtained here for the depth of the C s entrance-channel well in CH 3 F + Li is similar to the value of 2100 cm −1 obtained for the HF + Li interaction. 95 Soldán et al 94 reported well depths for the interactions between various alkali-metal atoms and the NH molecule. For the lowest quartet state at linear A-NH geometries, they are 1799.1, 651.3, 784.7, and 709.3 cm −1 for Li, Na, K, and Rb, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The value of 2073 cm −1 obtained here for the depth of the C s entrance-channel well in CH 3 F + Li is similar to the value of 2100 cm −1 obtained for the HF + Li interaction. 95 Ref. 94 reported well depths for the interactions between various alkali-metal atoms and the NH molecule.…”

Section: Interactionmentioning

confidence: 99%

Reactions between cold methyl halide molecules and alkali-metal atoms

Lutz

Hutson

2014

The Journal of Chemical Physics

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We investigate the potential energy surfaces and activation energies for reactions between methyl halide molecules CH 3 X (X = F, Cl, Br, I) and alkali-metal atoms A (A = Li, Na, K, Rb) using high-level ab initio calculations. We examine the anisotropy of each intermolecular potential energy surface (PES) and the mechanism and energetics of the only available exothermic reaction pathway, CH 3 X + A → CH 3 + AX. The region of the transition state is explored using two-dimensional PES cuts and estimates of the activation energies are inferred. Nearly all combinations of methyl halide and alkali-metal atom have positive barrier heights, indicating that reactions at low temperatures will be slow.

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“…Some well-known examples are alkali hydrogen halide exchange reactions (e.g. Li+HF→LiF+H) [4][5][6][7], collisional electron transfer reactions (e.g. Na+I→Na + +I − ) [8][9][10] and reactions involving hydrogen (e.g.…”

Section: Introductionmentioning

confidence: 99%

Density functional theory of electron transfer beyond the Born-Oppenheimer approximation: Case study of LiF

Requist

Gross

2018

The Journal of Chemical Physics

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We perform model calculations for a stretched LiF molecule, demonstrating that nonadiabatic charge transfer effects can be accurately and seamlessly described within a density functional framework. In alkali halides like LiF, there is an abrupt change in the ground state electronic distribution due to an electron transfer at a critical bond length R = R, where an avoided crossing of the lowest adiabatic potential energy surfaces calls the validity of the Born-Oppenheimer approximation into doubt. Modeling the R-dependent electronic structure of LiF within a two-site Hubbard model, we find that nonadiabatic electron-nuclear coupling produces a sizable elongation of the critical R by 0.5 bohr. This effect is very accurately captured by a simple and rigorously derived correction, with an M prefactor, to the exchange-correlation potential in density functional theory, M = reduced nuclear mass. Since this nonadiabatic term depends on gradients of the nuclear wave function and conditional electronic density, ∇χ(R) and ∇n(r, R), it couples the Kohn-Sham equations at neighboring R points. Motivated by an observed localization of nonadiabatic effects in nuclear configuration space, we propose a local conditional density approximation-an approximation that reduces the search for nonadiabatic density functionals to the search for a single function y(n).

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New Potential Energy Surface Features for the Li + HF → LiF + H Reaction

Cited by 11 publications

References 46 publications

Quantum dynamics of tunneling dominated reactions at low temperatures

Quantum dynamics of tunneling dominated reactions at low temperatures

Reactions between cold methyl halide molecules and alkali-metal atoms

Density functional theory of electron transfer beyond the Born-Oppenheimer approximation: Case study of LiF

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