A new interpretation for the structure of the VN bands of ethylene

Buenker, Robert J.; Peyerimhoff, Sigrid D.; Hsu, H. L.

doi:10.1016/0009-2614(71)80533-x

Cited by 123 publications

(38 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Another problem encountered in previous theoretical studies was that the highest level of theory used was the Hartree-Fock method. Hartree-Fock theory is known to overestimate the vibrational frequencies, although a The value in brackets under ∆Ee(UHF) is the average of the barrier obtained by fitting eq 1 to the cc-pV(3,4,5)Z and aug-cc-pV (3,4,5) HartreeFock energies. The value in brackets under δMP2 is the average of the barrier obtained by fitting eq 2 to the cc-pV(3,4)Z and aug-cc-pV(3,4) MP2 energies.…”

Section: Vibrational Analysismentioning

confidence: 99%

The Equilibrium Geometry, Harmonic Vibrational Frequencies, and Estimated ab Initio Limit for the Barrier to Planarity of the Ethylene Radical Cation

et al. 2002

View full text Add to dashboard Cite

The equilibrium geometry, barrier to planarity, and harmonic vibrational frequencies were determined theoretically for the ground state of the ethylene radical cation using several quantum mechanical methods and basis sets. The minimum-energy structure is a nonplanar D 2 conformer separated from its symmetry equivalent by a planar transition state. The CCSD(T)/cc-pVTZ level of theory obtained an equilibrium C-C bond length and torsion angle of 1.4004 Å and 21.0°, respectively, which are 0.005 Å and 4.0°less than the experimentally derived values of Köppel et al. [J. Chem. Phys. 1978, 69, 4252]. The documented reliability of CCSD(T)/cc-pVTZ equilibrium geometries might call into question the experimentally derived geometry. In addition, the barrier to planarity was determined using a series of basis sets and methods aimed at reaching the complete-basis-set limit. The final vibrationless barrier was determined to be 116 ( 35 cm -1 . Also, to aid in the interpretation of a recent infrared cavity-ring-down experiment, the harmonic vibrational frequencies were determined at the CCSD(T)/TZ2P level of theory. After the harmonic frequencies were scaled by a factor to account for incompleteness in the basis set and electron correlation treatment, the difference between the theoretically and experimentally deduced ω 7 (b 1 ) frequencies was a mere 1.4%.

show abstract

Section: Vibrational Analysismentioning

confidence: 99%

The Equilibrium Geometry, Harmonic Vibrational Frequencies, and Estimated ab Initio Limit for the Barrier to Planarity of the Ethylene Radical Cation

et al. 2002

View full text Add to dashboard Cite

show abstract

“…6 As a consequence this transition is supposed to show a nonvertical behavior. Starting from the experimental data, the "experimental vertical excitation energy" can be obtained following different approaches [6][7][8][9][10] and it has been estimated to be in the range 7.8 6 -8.0 10 eV. On the other hand Müller et al argued in a recent article 11 that "it is not necessary to refer to nonadiabatic effect in order to achieve agreement with the experiments data".…”

Section: Introductionmentioning

confidence: 96%

On the nature of the π → π* ionic excited states: The V state of ethene as a prototype

2008

View full text Add to dashboard Cite

This article addresses an analysis of the physical effects required for the correct description of the ionic pi --> pi* excited states in the frame of ab initio quantum chemistry, using the ionic V state of the ethene molecule as an example. The importance of the dynamic sigma polarization (absent in methods where the sigma skeleton is treated at a mean-field level) has been recognized by many authors in the past. In this article a new physical effect is described, i.e. the spatial contraction of the pi and pi* molecular orbitals (or of the local p atomic orbitals) originated from the reduction of the ionicity due to the dynamic sigma polarization. Such an effect is a second-order effect (it appears only as a consequence of the dynamic sigma polarization) but it cannot be ignored. Many of the difficulties found in the past in the calculation of the vertical excitation energy of the ionic states are attributed to an incomplete description of this contraction, while the few successes have been obtained when it has been fortuitously introduced by ad hoc procedures or when it is described in a brute force approach. Various strategies are proposed to allow for the spatial contraction of the p atomic orbitals. If this effect is considered at the orbital optimization step, it is shown that for the V state of ethene no Rydberg/valence mixing occurs and a simple perturbation correction (to the second order in the energy) on the pi --> pi* singly excited configuration gives stable results with respect to the computational parameters and in good agreement with the experimental findings and with the best theoretical calculations. Moreover, our results confirm the indication of Müller et al. (J Chem Phys 1999, 110, 7176) that the transition to the V state of ethene conforms to the Franck-Condon principle and that it is not necessary to appeal to a nonvertical transition to interpret the experimental data. The strategy reported in this article for ethene can be in principle generalized to the pi --> pi* ionic excited states of other molecules.

show abstract

“…22,23 The coupling of the V and Rydberg states has been discussed in a number of previous studies. [24][25][26][27][28][29] In the simulation of the ethylene absorption spectrum, Martinez and co-workers found that the coupling of the π 3s Rydberg state with the V state had to been taken into account in order to reproduce the experimentally observed doublet-like structure. 29 FIG.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast non-adiabatic dynamics of methyl substituted ethylenes: The π3s Rydberg state

Boguslavskiy

Schalk

et al. 2011

The Journal of Chemical Physics

View full text Add to dashboard Cite

Excited state unimolecular reactions of some polyenes exhibit localization of their dynamics at a single ethylenic double bond. Here we present studies of the fundamental photophysical processes in the ethylene unit itself. Combined femtosecond time-resolved photoelectron spectroscopy (TR-PES) and ab initio quantum chemical calculations was applied to the study of excited state dynamics in cis-butene, trans-butene, trimethylethylene, and tetramethylethylene, following initial excitation to their respective π 3s Rydberg states. The wavelength dependence of the π 3s Rydberg state dynamics of tetramethylethylene was investigated in more detail. The π 3s Rydberg to ππ * valence state decay rate varies greatly with substituent: the 1,2-di-and tri-methyl substituted ethylenes (cis-butene, trans-butene, and trimethylethylene) show an ultrafast decay (∼20 fs), whereas the fully methylated tetramethylethylene shows a decay rate of 2 to 4 orders of magnitude slower. These observations are rationalized in terms of topographical trends in the relevant potential energy surfaces, as found from ab initio calculations: (1) the barrier between the π 3s state and the ππ* state increases with increasing methylation, and (2) the π 3s/ππ* minimum energy conical intersection displaces monotonically away from the π 3s Franck-Condon region with increasing methylation. The use of systematic methylation in combination with TRPES and ab initio computation is emerging as an important tool in discerning the excited state dynamics of unsaturated hydrocarbons.

show abstract

A new interpretation for the structure of the VN bands of ethylene

Cited by 123 publications

References 22 publications

The Equilibrium Geometry, Harmonic Vibrational Frequencies, and Estimated ab Initio Limit for the Barrier to Planarity of the Ethylene Radical Cation

The Equilibrium Geometry, Harmonic Vibrational Frequencies, and Estimated ab Initio Limit for the Barrier to Planarity of the Ethylene Radical Cation

On the nature of the π → π* ionic excited states: The V state of ethene as a prototype

Ultrafast non-adiabatic dynamics of methyl substituted ethylenes: The π3s Rydberg state

Contact Info

Product

Resources

About