Ab Initio Anharmonic Vibrational Analyses of Non-Rigid Molecules

Allen, Wesley D.; East, Allan L. L.; Császár, Attila G.

doi:10.1007/978-94-011-2074-6_17

Cited by 112 publications

(93 citation statements)

References 63 publications

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“…The FPA 19,20 relative energies are obtained by single-point computations at the above-defined geometries considering (c) scalar relativistic corrections (∆ rel ) as difference between the second-order Douglas-Kroll 29 and non-relativistic AE-CCSD(T)/aug-cc-pCVQZ energies.…”

Section: A Computational Detailsmentioning

confidence: 99%

“…The benchmark FPA 19,20 classical relative energies of the above-mentioned stationary points are given in Tables I-III and a summary of the FPA results including ZPE-corrected adiabatic energies is given in Table IV. As Table I shows, electron correlation plays an important role in the accurate determination of the Walden inversion barrier height.…”

Section: B Structures and Relative Energies Of The Stationary Pointsmentioning

confidence: 99%

“…II, we characterize the stationary points of the global PES of the F − + CH 3 F reaction and provide benchmark relative energies employing the composite ab initio focalpoint analysis (FPA) 19,20 approach. The FPA method employs a multidimensional extrapolation scheme to approach the complete basis set (CBS) limit of the relativistic all-electron full configuration interaction energy.…”

Section: Introductionmentioning

confidence: 99%

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Accurate ab initio potential energy surface, thermochemistry, and dynamics of the F− + CH3F SN2 and proton-abstraction reactions

Szabó

Telekes

Czakó

2015

The Journal of Chemical Physics

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Articles you may be interested inWe develop a full-dimensional global analytical potential energy surface (PES) for the F − + CH 3 F reaction by fitting about 50 000 energy points obtained by an explicitly correlated composite method based on the second-order Møller-Plesset perturbation-F12 and coupled-cluster singles, doubles, and perturbative triples-F12a methods and the cc-pVnZ-F12 [n = D, T] basis sets. The PES accurately describes the (a) back-side attack Walden inversion mechanism involving the pre-and post-reaction (b) ion-dipole and (c) hydrogen-bonded complexes, the configuration-retaining (d) front-side attack and (e) double-inversion substitution pathways, as well as (f) the proton-abstraction channel. The benchmark quality relative energies of all the important stationary points are computed using the focal-point analysis (FPA) approach considering electron correlation up to coupled-cluster singles, doubles, triples, and perturbative quadruples method, extrapolation to the complete basis set limit, core-valence correlation, and scalar relativistic effects. The FPA classical(adiabatic) barrier heights of (a), (d), and (e) are −0.45(−0.61), 46.07(45.16), and 29.18(26.07) kcal mol −1 , respectively, the dissociation energies of (b) and (c) are 13.81(13.56) and 13.73(13.52) kcal mol −1 , respectively, and the endothermicity of (f) is 42.54(38.11) kcal mol −1 . Quasiclassical trajectory computations of cross sections, scattering (θ) and initial attack (α) angle distributions, as well as translational and internal energy distributions are performed for the F − + CH 3 F(v = 0) reaction using the new PES. Apart from low collision energies (E coll ), the S N 2 excitation function is nearly constant, the abstraction cross sections rapidly increase with E coll from a threshold of ∼40 kcal mol −1 , and retention trajectories via double inversion are found above E coll = ∼30 kcal mol −1 , and at E coll = ∼50 kcal mol −1 , the front-side attack cross sections start to increase very rapidly. At low E coll , the indirect mechanism dominates (mainly isotropic backward-forward symmetric θ distribution and translationally cold products) and significant long-range orientation effects (isotropic α distribution) and barrier recrossings are found. At higher E coll , the S N 2 reaction mainly proceeds with direct rebound mechanism (backward scattering and hot product translation). C 2015 AIP Publishing LLC. [http://dx

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Section: A Computational Detailsmentioning

confidence: 99%

Section: B Structures and Relative Energies Of The Stationary Pointsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Accurate ab initio potential energy surface, thermochemistry, and dynamics of the F− + CH3F SN2 and proton-abstraction reactions

Szabó

Telekes

Czakó

2015

The Journal of Chemical Physics

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“…[155,156]) módszerére hagyatkoztunk. Míg az algebrai aspektus, amely az FCRN-ek szerkezeti jellemzésében és azok koncentráció-idő függvényeinek elő-állításában rajzolódott ki, a formálkinetika eszközeinek tárházát gazdagítja, addig az FPA megközelítés, amelynek nyomán megannyi pontos termokémiai modellt vezettek már be az irodalomban, a számításos kémia egyik leghatékonyabb modellépítési elvének tekinthető.…”

Section: öSszefoglalásunclassified

Konformációváltozások kinetikájának modellezése elsőrendű reakcióhálózatokkal

Tóbiás

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“…A focal-point 43,44 analízis (FPA) egy általános, a felhasználó által átgondolt és ésszerűen felépített sémán alapuló modell, melyet eredetileg nagyfelbontású molekulaspektroszkópiai számításokhoz dolgoztak ki a 90-es évek elején. Mivel a módszer kiválóan alkalmas nagy pontosságú relatív energiakülönbségek számítására, így használata a termokémiában gyorsan elterjedt és kidolgozása óta számos kisebb molekuláris rendszer esetén alkalmazták referenciaadatok előállítására.…”

Section: A Focal-point Analízisunclassified

Légkörkémiai fontosságú kisebb gyökök és molekulák ab initio termokémiája

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Ab Initio Anharmonic Vibrational Analyses of Non-Rigid Molecules

Cited by 112 publications

References 63 publications

Accurate ab initio potential energy surface, thermochemistry, and dynamics of the F− + CH3F SN2 and proton-abstraction reactions

Accurate ab initio potential energy surface, thermochemistry, and dynamics of the F− + CH3F SN2 and proton-abstraction reactions

Konformációváltozások kinetikájának modellezése elsőrendű reakcióhálózatokkal

Légkörkémiai fontosságú kisebb gyökök és molekulák ab initio termokémiája

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