Excited states of acrolein: abinitio model studies on α,β-unsaturated carbonyl compounds

1982 ◽  
Vol 60 (5) ◽  
pp. 601-606 ◽  
Author(s):  
Katherine Valenta ◽  
Friedrich Grein
Keyword(s):  
Excited State ◽  
Excited States ◽  
Carbonyl Compound ◽  
Carbonyl Compounds ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Model Studies ◽  
Unsaturated Carbonyl Compound ◽  
Vertical Excitation Energies

As an explanation of the stereochemistry of photoaddition between α,β-unsaturated carbonyl compounds and olefins, Wiesner suggested that the excited state of the α,β-unsaturated carbonyl compound is pyramidal at the β-carbon. It is shown by abinitio SCF and CI studies that for acrolein in the 1nπ*, 3nπ*, and 3ππ* excited states the β-carbon remains planar. In addition, vertical excitation energies for the 1nπ* and 1ππ*, and adiabatic excitation energies for the 1nπ* and 3nπ* states of trans-acrolein have been calculated.

The structure and vertical excitation energies of the chlorothioformyl radical, ClCS: implications for the photofragmentation of thiophosgene

1993 ◽  
Vol 71 (1) ◽  
pp. 112-117 ◽  
Author(s):  
M. Hachey ◽  
F. Grein ◽  
R. P. Steer
Keyword(s):  
Energy Level ◽  
Ab Initio ◽  
Excited States ◽  
Ground State ◽  
Excited Electronic State ◽  
Excitation Energies ◽  
Electronically Excited States ◽  
Vertical Excitation ◽  
Electronically Excited ◽  
Vertical Excitation Energies

Ab initio CI studies have been performed to determine the geometry of the ground and first electronically excited states of the chlorothioformyl radical, ClCS, and the vertical excitation energies of its ten lowest doublet states and two lowest quartet states. The results are used to construct a more complete energy level correlation diagram for the photofragmentation of Cl2CS. The lowest excited electronic state of ClCS lies only 0.79 eV (adiabatic) above the ground state. Its discovery indicates that the results of previous photofragmentation experiments may need to be reinterpreted.

scholarly journals Ab initio studies of two pyrimidine derivatives as possible photo-switch systems

Open Physics ◽  
2013 ◽  
Vol 11 (9) ◽  
Author(s):  
András Csehi ◽  
Clemens Woywod ◽  
Gábor Halász ◽  
Ágnes Vibók
Keyword(s):  
Excited State ◽  
Hydrogen Transfer ◽  
Covalent Bond ◽  
Excitation Energies ◽  
Complete Active Space ◽  
Vertical Excitation ◽  
Singlet States ◽  
Self Consistent Field ◽  
Intramolecular Hydrogen ◽  
Vertical Excitation Energies

AbstractThe six lowest lying electronic singlet states of 8-(pyrimidine-2-yl)quinolin-ol and 2-(4-nitropyrimidine-2-yl)ethenol have been studied theoretically using the complete active space self-consistent-field (CASSCF) and M’ller-Plesset second-order perturbation theory (MP2) methods. Both molecules can be viewed as consisting of a frame and a crane component. As a possible mechanism for the excited-state relaxation process an intramolecular hydrogen transfer promoted by twisting around the covalent bond connecting the molecular frame and crane moieties has been considered. Based on this idea we have attempted to derive abstracted photochemical pathways for both systems. Geometry optimizations for the construction of hypothetical reaction coordinates have been performed at the MP2 level of theory while the CASSCF approach has been employed for the calculation of vertical excitation energies along the pathways. The results of the calculations along the specific twisting displacements investigated in this study do not support the notion of substantial twisting activity upon excitation of any of the five excited states at the planar terminal structures of the torsion coordinates of both molecules. However, the present analysis should be considered only as a first, preliminary step towards an understanding of the photochemistry of the two candidate compounds. For example, we have not performed any excited state geometry optimizations so far and the estimates of vertical excitation energies do not take dynamical electron correlation into account. Further work on this subject is in progress.

scholarly journals Benchmarking Density Functional Approximations for Excited-State Properties of Fluorescent Dyes

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7434
Author(s):  
Anna M. Grabarz ◽  
Borys Ośmiałowski
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Fluorescent Dyes ◽  
Dipole Moments ◽  
Photophysical Properties ◽  
Excitation Energies ◽  
Data Set ◽  
Vertical Excitation ◽  
A Minor ◽  
Vertical Excitation Energies

This study presents an extensive analysis of the predictive power of time-dependent density functional theory in determining the excited-state properties of two groups of important fluorescent dyes, difluoroboranes and hydroxyphenylimidazo[1,2-a]pyridine derivatives. To ensure statistically meaningful results, the data set is comprised of 85 molecules manifesting diverse photophysical properties. The vertical excitation energies and dipole moments (in the electronic ground and excited states) of the aforementioned dyes were determined using the RI-CC2 method (reference) and with 18 density functional approximations (DFA). The set encompasses DFAs with varying amounts of exact exchange energy (EEX): from 0% (e.g., SVWN, BLYP), through a medium (e.g., TPSSh, B3LYP), up to a major contribution of EEX (e.g., BMK, MN15). It also includes range-separated hybrids (CAM-B3LYP, LC-BLYP). Similar error profiles of vertical energy were obtained for both dye groups, although the errors related to hydroxyphenylimidazopiridines are significantly larger. Overall, functionals including 40–55% of EEX (SOGGA11-X, BMK, M06-2X) ensure satisfactory agreement with the reference vertical excitation energies obtained using the RI-CC2 method; however, MN15 significantly outperforms them, providing a mean absolute error of merely 0.04 eV together with a very high correlation coefficient (R2 = 0.98). Within the investigated set of functionals, there is no single functional that would equally accurately determine ground- and excited-state dipole moments of difluoroboranes and hydroxyphenylimidazopiridine derivatives. Depending on the chosen set of dyes, the most accurate μGS predictions were delivered by MN15 incorporating a major EEX contribution (difluoroboranes) and by PBE0 containing a minor EEX fraction (hydroxyphenylimidazopiridines). Reverse trends are observed for μES, i.e., for difluoroboranes the best results were obtained with functionals including a minor fraction of EEX, specifically PBE0, while in the case of hydroxyphenylimidazopiridines, much more accurate predictions were provided by functionals incorporating a major EEX contribution (BMK, MN15).

scholarly journals Molecular Vertical Excitation Energies Studied with First-Order RASSCF (RAS[1,1]): Balancing Covalent and Ionic Excited States

2019 ◽  
Vol 123 (25) ◽  
pp. 5223-5230 ◽  
Author(s):  
Thierry Tran ◽  
Javier Segarra-Martí ◽  
Michael J. Bearpark ◽  
Michael A. Robb
Keyword(s):  
Excited States ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
First Order ◽  
Vertical Excitation Energies

The electronic structure of the first row hydrides BH, CH, NH, OH and FH II. Excited states

1959 ◽  
Vol 249 (1258) ◽  
pp. 402-413 ◽  
Keyword(s):  
Electronic Structure ◽  
Excited States ◽  
Electron Correlation ◽  
Ground States ◽  
Oscillator Strengths ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Experimental Values ◽  
Vertical Excitation Energies ◽  
Dipole Length

Previous calculations on the ground states of the hydrides are extended to include the stable excited states. The ab initio orbital calculations predict vertical excitation energies which differ from the experimental values by as much as 2eV. However, when allowance is made for the effects of atomic electron correlation all errors in the calculated excitation energies become less than 0·2eV. The locations of excited states of different multiplicities from those of the ground states are predicted to within this accuracy. The oscillator strengths of allowed transitions from the ground states are calculated using both the dipole-length and dipole-velocity formulae. The dipole-length values are in fair agreement with the only experimental value available (for OH 2 ll → 2 ∑ + ), whereas the dipole-velocity values are much too large. Possible improvements in the accuracy of the calculations are discussed.

COSMO-RI-ADC(2) excitation energies and excited state gradients

2018 ◽  
Vol 20 (24) ◽  
pp. 16354-16363 ◽  
Author(s):  
Sarah Karbalaei Khani ◽  
Alireza Marefat Khah ◽  
Christof Hättig
Keyword(s):  
Excited State ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Vertical Excitation Energies

Evaluating vertical excitation energies and excited state analytic gradients in solution at COSMO-ADC(2).

Exploring the Accuracy of a Low Scaling Similarity Transformed Equation of Motion Method for Vertical Excitation Energies

2017 ◽  
Vol 14 (1) ◽  
pp. 72-91 ◽  
Author(s):  
Achintya Kumar Dutta ◽  
Marcel Nooijen ◽  
Frank Neese ◽  
Róbert Izsák
Keyword(s):  
Equation Of Motion ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Motion Method ◽  
Vertical Excitation Energies
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