Tunneling dynamics in isotopically substituted malonaldehyde. Comparison between symmetric and asymmetric species

Bosch, Enric; Moreno, Miquel; Lluch, José M.

doi:10.1021/ja00032a021

Cited by 37 publications

(14 citation statements)

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“…Until the 90ies, this barrier height has been found [11,14] ranging from 4.7 to 10.0 kcal·mol -1 , the lowest value coming from the work of Frisch et al [13] which emphasizes the role of electron correlation. Consistently, more recent and accurate calculations [15][16][17][18][19][20][21][22][23][24][25][26][27] agree with lower values between 3.1 and 4.6 kcal·mol -1 . Discrepancies originate from the difficulty of describing the complex multidimensional dynamics of this proton tunnelling.…”

Section: Introductionsupporting

confidence: 64%

Comparative study of structure and photo-induced reactivity of malonaldehyde and acetylacetone isolated in nitrogen matrices

Trivella¹,

Coussan²,

Chiavassa³

et al. 2006

Low Temperature Physics

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Structure and reactivity of the eight enolic forms (one chelated and seven non-chelated) of malonaldehyde and acetylacetone are compared through theoretical and experimental data. Ground-state geometries, energies, and vibrational frequencies are calculated with the B3LYP/6-311++G(2d,2p) model chemistry. The electronic delocalisation as well as the cis/trans rotamer properties are analysed. The hydrogen bond strength of the chelated forms can be estimated by the energy difference between chelated and non-chelated forms, and its enhancement due to methyl-induced electron release is estimated at 1.7 kcal·mol -1 . UV-and IR-induced reactivity of molecules isolated in nitrogen matrices is studied by means of FT-IR spectrometry. Interconversion between rotamers is the main process observed for both molecules, only some among the seven non-chelated forms being created.PACS: 36.20.Ng, 31.15.Ar

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Section: Introductionsupporting

confidence: 64%

Comparative study of structure and photo-induced reactivity of malonaldehyde and acetylacetone isolated in nitrogen matrices

Trivella¹,

Coussan²,

Chiavassa³

et al. 2006

Low Temperature Physics

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“…However, the number of degrees of freedom involved in the tropolone makes this calculation unattainable. To circumvent this problem we have fitted 19,28 for each studied case a two-dimensional quartic polynomial approximation that retains the main features of the true multidimensional surface that are relevant in tunneling dynamics. This reduces the problem to the diagonalization of a bidimensional Hamiltonian that can be performed using an appropriate basis set.…”

Section: B Tunneling Modelmentioning

confidence: 99%

“…In previous works 19, 28 the four adjusted parameters a, b, c, and were fitted so that the lengths and the energy barriers of the intrinsic reaction coordinate ͑IRC͒, which passes through the transition state, and the ''direct'' linear reaction path ͑LRP͒ on the bidimensional surface coincided with the ''true'' IRC and LRP values on the multidimensional surfaces.…”

Section: B Tunneling Modelmentioning

confidence: 99%

Bidimensional tunneling splitting in the Ã 1B2 and X̃ 1A1 states of tropolone

Paz

Moreno

Lluch

1995

The Journal of Chemical Physics

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The intramolecular proton transfer in tropolone has been theoretically analyzed. Ab initio calculations using a variety of basis sets have been performed for both the singlet ground state (X 1 A 1 ) and the first excited singlet state (Ã 1 B 2 ). A configuration interaction all single excitation method ͑CIS͒ has been used to deal with the excited singlet state. Tunneling splittings in both electronic states have been obtained by fitting a bidimensional surface into the ab initio results. This way, a new strategy designed to avoid calculations of the intrinsic reaction coordinate ͑IRC͒, which require a very long computer time, is proposed and shown to give accurate results. Our calculations provide a theoretical interpretation of previous extensive spectroscopical data from which the tunneling splitting for the excited Ã 1 B 2 state was shown to be clearly higher than for the ground X 1 A 1 state. Finally, the experimentally observed diminution of the splitting upon deuteration of the transferring hydrogen is also accounted for by our theoretical results.

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“…We expect the error due to approximation to be very small as already a polynomial of the order of 4 gives satisfying results if it is used as analytical surface for double wells. 8,50 Now, both important values from Eq. ͑1͒ are theoretically derived, the last, but very important question is the determination of the tunneling path.…”

Section: Computation Of S 0 and Amentioning

confidence: 99%

An accurate semiclassical method to predict ground-state tunneling splittings

Tautermann

Voegele

Loerting

et al. 2002

The Journal of Chemical Physics

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A new method for calculating the ground-state tunneling splitting is presented. It is based on the semiclassical theory including recently derived corrections and it is the first method, which explicitly takes into account the whole conformational space between the minima and the transition state. The density-functional theory is used to determine the qualitative shape of the potential energy surface ͑PES͒ and high level ab initio calculations provide information about the stationary points. With a dual level scheme, the low-level energy surface is mapped onto the high-level points to get a good quantitative description of the high-level PES. Therefore, the new method requires no adjustment of additional parameters like scaling of the energy barrier as is necessary in other methods. Once the high-level PES is calculated, the most probable tunneling paths are determined with a global optimization procedure. Along this representative tunneling path, the tunneling splitting is calculated with additional consideration of zero-point vibrational effects. The method is applied to three molecular systems, namely hydrofluoric acid dimer, malonaldehyde, and tropolone. These systems were chosen because their energy barriers differ strongly ͑1 kcal/mol-7 kcal/mol͒. The predicted tunneling splittings agree very well with the experimental ones, therefore, we expect our method to be generally applicable, independent of the magnitude of the energy barrier.

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Tunneling dynamics in isotopically substituted malonaldehyde. Comparison between symmetric and asymmetric species

Cited by 37 publications

References 0 publications

Comparative study of structure and photo-induced reactivity of malonaldehyde and acetylacetone isolated in nitrogen matrices

Comparative study of structure and photo-induced reactivity of malonaldehyde and acetylacetone isolated in nitrogen matrices

Bidimensional tunneling splitting in the Ã 1B2 and X̃ 1A1 states of tropolone

An accurate semiclassical method to predict ground-state tunneling splittings

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