High-dimensional ab initio potential energy surfaces for reaction dynamics calculations

Bowman, Joel M.; Czakó, Gábor; Fu, Bina

doi:10.1039/c0cp02722g

Cited by 273 publications

(269 citation statements)

References 155 publications

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“…Reaction dynamics simulations require the knowledge of the PES, which governs the motion of the atoms in a chemical reaction [15][16][17] . Full-dimensional analytical PESs that describe both the back-and front-side attack mechanisms have not been developed for S N 2 reactions.…”

Section: Resultsmentioning

confidence: 99%

“…This composite method provides AE-CCSD(T)/aug-cc-pCVQZ quality results within a root-mean-square error of only 0.35 kcal mol À 1 . The analytical representation of the PES is obtained by a fifth-order fit using the permutationally invariant polynomial approach 15,16 based on Morse-like variables, exp(-r ij /a), where r ij are the inter-atomic distances and a ¼ 3 bohr. The linear leastsquares fit, with weight of E 0 /(E þ E 0 ), where E 0 ¼ 31 kcal mol À 1 and E is relative to the global minimum, provides 3,313 coefficients.…”

Section: Methodsmentioning

confidence: 99%

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Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

2015

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Stereo-specific reaction mechanisms play a fundamental role in chemistry. The back-side attack inversion and front-side attack retention pathways of the bimolecular nucleophilic substitution (S N 2) reactions are the textbook examples for stereo-specific chemical processes. Here, we report an accurate global analytic potential energy surface (PES) for the F À þ CH 3 Cl S N 2 reaction, which describes both the back-side and front-side attack substitution pathways as well as the proton-abstraction channel. Moreover, reaction dynamics simulations on this surface reveal a novel double-inversion mechanism, in which an abstraction-induced inversion via a FH Á Á Á CH 2 Cl À transition state is followed by a second inversion via the usual [F Á Á Á CH 3 Á Á Á Cl] À saddle point, thereby opening a lower energy reaction path for retention than the front-side attack. Quasi-classical trajectory computations for the F À þ CH 3 Cl(n 1 ¼ 0, 1) reactions show that the front-side attack is a fast direct, whereas the double inversion is a slow indirect process.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

2015

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“…Recent progress in the determination of PESs by ab initio methods [1] has allowed quantum-mechanical (QM) or quasiclassical trajectory treatments of the reaction dynamics to reproduce the integral and differential cross sections (ICSs and DCSs) obtained in high-resolution crossed-beam experiments for prototypical four-atom HD þ OH ! H 2 O þ D [2] and sixatom Cl þ CHD 3 !…”

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confidence: 99%

Dynamics of theS(D21)+HD(j=0
Lara
¹
,
Chefdeville
²
,
Hickson
³

et al. 2012
Phys. Rev. Lett.
41
3
29
0
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We report integral cross sections for the Sð 1 D 2 Þ þ HDðj ¼ 0Þ ! DS þ H and HS þ D reaction channels obtained through crossed-beam experiments reaching collision energies as low as 0.46 meV and from adiabatic time-independent quantum-mechanical calculations. While good overall agreement with experiment at energies above 10 meV is observed, neither the product channel branching ratio nor the low-energy resonancelike features in the HS þ D channel can be theoretically reproduced. A nonadiabatic treatment employing highly accurate singlet and triplet potential energy surfaces is clearly needed to resolve the complex nature of the reaction dynamics. DOI: 10.1103/PhysRevLett.109.133201 PACS numbers: 34.50.Lf, 31.15.xj, 31.50.Àx, 37.20.+j For theory to furnish a good description of elementary gas-phase reaction dynamics requires the use of a highly accurate potential energy surface (PES) describing the passage from reagents to products. Recent progress in the determination of PESs by ab initio methods [1] has allowed quantum-mechanical (QM) or quasiclassical trajectory treatments of the reaction dynamics to reproduce the integral and differential cross sections (ICSs and DCSs) obtained in high-resolution crossed-beam experiments for prototypical four-atom [3,4]. This has followed the exquisite agreement between theory and experiment found for the benchmark three-atom 7,8] reactions for which resonance features have been fully rationalized. However, all these studies have been performed at medium to high collision energies to be able to surmount the classical energy barriers, between 70 and 300 meV, which characterize these reactions. The lowest collision energy attained so far is E T ¼ 6 meV in the case of the F þ H 2 reaction for which substantial tunneling through the barrier occurs [8]. An important question arises: Will the accuracy of electronic structure calculations (currently recognized to be within the 10-40 meV range) be sufficient to reproduce experimental studies of reactive processes occurring at very low collision energies? When only a few partial waves, characterized by a given value of total angular momentum J which is conserved throughout the collision, contribute to the dynamics, individual quantum effects become apparent and the slightest inaccuracy of the PES can lead to dramatic differences in the theoretical results. Multisurface effects arising from the open-shell nature of the reactants may also start to play a dominant role as recently outlined for the Fð 2 P 1=2 Þ þ H 2 ðj ¼ 0Þ reaction in which a pronounced resonance peak is predicted in the ICSs around E T ¼ 0:2-0:3 meV [9].Despite the tremendous advances in the generation of cold atomic and molecular species by Stark or Zeeman deceleration, buffer-gas, or laser cooling [10,11], very few experiments are able to approach the cold energy regime at temperatures below T ¼ 1 K. One can cite the recent buffer-gas cooling study of the Li þ CaH ! LiH þ Ca reaction at T ¼ 1 K [12] but experiments of this type provide rate coefficients, not cro...

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“…[69,71,75] Importantly for applications to materials modeling and design, this method has been shown to provide highaccuracy PESs for bulk materials as well as surfaces and nanostructures, [68,69,72,74,76,77] where other highly accurate approaches developed for molecular systems [22,67] are impractical.…”

Section: Review Wwwq-chemorgmentioning

confidence: 99%

“…We have used this strategy in combination with symmetrizing the NN output and found that it works well in as many as 15 dimensions. [26,29] Guo and coworkers [62][63][64][65][66] [22,67] of interatomic coordinates. Interatomic coordinates make this approach systematic and easy to generalize.…”

Section: Symmetry Issuesmentioning

confidence: 99%

Neural network‐based approaches for building high dimensional and quantum dynamics‐friendly potential energy surfaces

Manzhos

Dawes

Carrington

2014

Int J of Quantum Chemistry

196

148

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Development and applications of neural network (NN)-based approaches for representing potential energy surfaces (PES) of bound and reactive molecular systems are reviewed. Specifically, it is shown that when the density of ab initio points is low, NNs-based potentials with multibody or multimode structure are advantageous for representing high-dimensional PESs. Importantly, with an appropriate choice of the neuron activation function, PESs in the sum-of-products form are naturally obtained, thus addressing a bottleneck problem in quantum dynamics. The use of NN committees is also analyzed and it is shown that while they are able to reduce the fitting error, the reduction is limited by the nonrandom nature of the fitting error. The approaches described here are expected to be directly applicable in other areas of science and engineering where a functional form needs to be constructed in an unbiased way from sparse data.

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High-dimensional ab initio potential energy surfaces for reaction dynamics calculations

Cited by 273 publications

References 155 publications

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Dynamics of theS(D21)+HD(j=0
Lara
¹
,
Chefdeville
²
,
Hickson
³

et al. 2012
Phys. Rev. Lett.
41
3
29
0
View full text Add to dashboard Cite

Neural network‐based approaches for building high dimensional and quantum dynamics‐friendly potential energy surfaces

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High-dimensional ab initio potential energy surfaces for reaction dynamics calculations

Cited by 273 publications

References 155 publications

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Dynamics of theS(D21)+HD(j=0Lara1, Chefdeville2, Hickson3 et al. 2012Phys. Rev. Lett.413290View full textAdd to dashboardCite

Neural network‐based approaches for building high dimensional and quantum dynamics‐friendly potential energy surfaces

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Resources

About

Dynamics of theS(D21)+HD(j=0
Lara
¹
,
Chefdeville
²
,
Hickson
³

et al. 2012
Phys. Rev. Lett.
41
3
29
0
View full text Add to dashboard Cite