Time-dependent coupled Hartree–Fock calculations of triplet excited states of closed-shell atoms

1985 ◽  
Vol 63 (10) ◽  
pp. 1278-1281 ◽  
Author(s):  
B. Kundu ◽  
P. K. Mukherjee
Keyword(s):  
Excited States ◽  
Excitation Spectrum ◽  
Reasonable Agreement ◽  
Closed Shell ◽  
Time Dependent ◽  
Perturbation Operator ◽  
Hartree Fock ◽  
Effective Form ◽  
Forbidden Transitions ◽  
Triplet Excited States

The nonrelativistic, time-dependent coupled Hartree–Fock theory has been applied to generate the excitation spectrum of two-electron atoms for the forbidden transitions 11S → n3S(n = 2, …, 8), and transition properties are estimated. A simple but effective form of the time-dependent perturbation operator is chosen to get such an excitation spectrum. Reasonable agreement is observed with the available experimental and theoretical estimates.

The structures and stabilities of singlet and triplet dithiatriazines: a computational study

1988 ◽  
Vol 66 (9) ◽  
pp. 2279-2284 ◽  
Author(s):  
R. E. Hoffmeyer ◽  
W.-T. Chan ◽  
J. D. Goddard ◽  
R. T. Oakley
Keyword(s):  
Excited States ◽  
Electron Correlation ◽  
Computational Study ◽  
Geometry Optimization ◽  
Hartree Fock ◽  
Structural Distortions ◽  
Energy Gaps ◽  
Jahn Teller ◽  
Moller Plesset ◽  
Triplet Excited States

Ab initio molecular orbital and Møller–Plesset perturbation theory calculations have been carried out on two model dithiatriazines RCN3S2 (R = H, NH2). With geometry optimization and the inclusion of electron correlation both of these dithiatriazines are predicted to be ground state singlets. Both molecules have low-lying triplet excited states, with energy gaps of 6.6 (R = H) and 13.0 (R = NH2) kcal mol−1. The singlet dithiatriazines distort from high (C2v) to low (Cs) symmetry, and these changes are important in determining the relative energies of the singlet and triplet molecules. The structural distortions experienced by these molecules are related to Hartree–Fock and Jahn–Teller instabilities in other thiazene heterocycles.

scholarly journals Multiresolution quantum chemistry in multiwavelet bases: excited states from time-dependent Hartree–Fock and density functional theory via linear response

2015 ◽  
Vol 17 (47) ◽  
pp. 31405-31416 ◽  
Author(s):  
Takeshi Yanai ◽  
George I. Fann ◽  
Gregory Beylkin ◽  
Robert J. Harrison
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemistry ◽  
Numerical Method ◽  
Excited States ◽  
Multiresolution Analysis ◽  
Linear Response ◽  
Density Functional ◽  
Time Dependent ◽  
Functional Theory ◽  
Hartree Fock

A fully numerical method for the time-dependent Hartree–Fock and density functional theory (TD-HF/DFT) with the Tamm–Dancoff (TD) approximation is presented in a multiresolution analysis (MRA) approach.

scholarly journals Theoretical investigation of the structural and spectroscopic properties of expanded metalloporphyrin complexes

2019 ◽  
Vol 6 (1) ◽  
pp. 181199 ◽  
Author(s):  
Jie Jiang ◽  
Shengwei Guo ◽  
Xiaorong Wang ◽  
Liyan Xu ◽  
Qiang Li ◽  
...  
Keyword(s):  
Excited States ◽  
Density Functional ◽  
Dft Method ◽  
Spectroscopic Properties ◽  
Time Dependent ◽  
Frontier Molecular Orbitals ◽  
Functional Theory ◽  
Long Wavelength ◽  
The Density Functional Theory ◽  
Triplet Excited States

The frontier molecular orbitals, UV–Vis absorption spectra, charge transfer (CT) and triplet excited states of 12 expanded D–A porphyrin/benzoporphyrin complexes were investigated using the density functional theory (DFT) method and time-dependent DFT in this work. The results showed that thiophene was an effective fragment for absorption of ‘long wavelength’, while the benzoporphyrin worked on the ‘short wavelength’, which was derived from its saddle-shaped structure; this expanded D–A conjugated system had a mild CT process with anthraquinone/isoindigo as acceptors and a strong CT process with naphtoquinone as acceptor. In addition, based on the simulation of the triplet state, the theoretical phosphorescence wavelength range of this series of derivatives was between 1000 and 1200 nm. This study is expected to assist the design of conjugated porphyrin for the field of porphyrin chemistry.

scholarly journals Synthesis, optical and electrochemical study of bipolar heterocyclic systems, including 1,2,4-oxadiazole moiety

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
D. G. Selivanova ◽  
O. A. Mayorova ◽  
A. A. Gorbunov ◽  
A. N. Vasyanin ◽  
M. V. Dmitriev ◽  
...  
Keyword(s):  
Excited States ◽  
Density Functional ◽  
Time Dependent ◽  
Electrochemical Studies ◽  
Absorption Data ◽  
Functional Theory ◽  
Conjugation Chain ◽  
Td Dft ◽  
Triplet Excited States ◽  
New Compounds

AbstractTwo new 3,5-dihetarylsubstituted 1,2,4- oxadiazoles 8 a,b, including N-alkyl substituted carbazole and thiophene moieties, were synthesized as potential components of materials for organic electronics devices. Optical and electrochemical properties of all new compounds were investigated. On the basis of the experimental UV absorption data, the values of bandgap energies equal to 3.44 eV (8a) and 3.05 eV (8b) were determined. The values of their ionization potentials, HOMO levels (−5.62 eV for 8a, −5.46 eV – for 8b), as well as their electron affinity levels, LUMO levels (−2.2 eV for 8a, −2.4 eV – for 8b), were calculated from the results of electrochemical studies. The energy of the triplet excited states of 8 a,b was defined with the help of time-dependent density functional theory (TD-DFT), comprising 2.68 eV (8a) and 2.32 eV (8b), where the greatest value of this parameter was for the compound with a shorter conjugation chain.

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