Excited and ionized states of free base porphin studied by the symmetry adapted cluster-configuration interaction (SAC-CI) method

Nakatsuji, Hiroshi; Hasegawa, Jun‐ya; Hada, Masahiko

doi:10.1063/1.470927

Cited by 173 publications

(156 citation statements)

References 47 publications

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“…The DFT/MRCI oscillator strengths of 0.485 and 0.660, respectively, support this assignment as well. In contrast, Nakatsuji and coworkers interpret the results of their SAC-CI calculations [30] in a different way. They assign the 2 1 B 3u state to the Bband and the 2 1 B 2u state to the N-band.…”

Section: Free-base Porphyrinmentioning

confidence: 81%

DFT/MRCI calculations on the excited states of porphyrin, hydroporphyrins, tetrazaporphyrins and metalloporphyrins

Parusel

2001

J. Porphyrins Phthalocyanines

107

105

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A combination of density functional theory and multi-reference configuration interaction methods (DFT/MRCI) has been applied to the calculation of electronic absorption spectra in a series of porphyrin-type molecules. The calculated excitation energies and oscillator strengths for free-base porphyrin (PH 2 ) are in excellent agreement with experiment for both lower and higher excited states which are characterized by a significant contribution of double excitations (b20%). The 4 1 B 2u , 4 1 B 3u , and 5 1 B 2u states are assigned to the L-band and the 7 1 B 3u state to the M-band. The results for the hydroporphyrins chlorin (CH 2 ) and bacteriochlorin (BH 2 ) are in agreement with the experimentally observed increase in intensity for the Q-bands relative to PH 2 . For BH 2 we predict a red shift of the Q x -band (0.2 eV) and a blue shift of the B-band (0.5-0.7 eV) in comparison to both PH 2 and CH 2 . For porphyrazine (PzH 2 ) and the commercial pigment phthalocyanine (PcH 2 ) the calculated oscillator strengths of the Qand B-bands are of comparable size explaining the intense color of PcH 2 . For the metalloporphyrins with magnesium (PMg) and zinc (PZn), the x-and y-polarized components of the Q-and B-bands collapse, due to the higher D 4h symmetry of the molecules. The calculations reproduce the slight, experimentally observed increase in the oscillator strength of the Q-band and the decrease for the B-band. These effects are ascribed to the electropositive nature of the metals relative to hydrogen. Except for the Q-bands, which are adequately described by the 'four-orbital model,' it is essential to account for excitations outside the four frontier orbitals as well as double and triple excitations for accurate reproduction of experimental data. We compare our results both with experiment and, where available, recent first-principle SAC-CI, MRMP, and TDDFT calculations.

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Section: Free-base Porphyrinmentioning

confidence: 81%

DFT/MRCI calculations on the excited states of porphyrin, hydroporphyrins, tetrazaporphyrins and metalloporphyrins

Parusel

2001

J. Porphyrins Phthalocyanines

107

105

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“…The CC methods employed most often have been the symmetry-adapted cluster configuration interaction (SAC-CI) approach, [25] the equation-of-motion coupled-cluster (EOM-CC) method (also the similarity-transformed STEOM-CC [26,27] ), and the hierarchy of linear-response CCx approaches. [28] Although they have different formulations, their results for the common truncated and non-approximated coupled-cluster models are similar.…”

Section: Propagator Approachesmentioning

confidence: 99%

Progress and Challenges in the Calculation of Electronic Excited States

2011

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A detailed understanding of the properties of electronic excited states and the reaction mechanisms that molecules undergo after light irradiation is a fundamental ingredient for following light-driven natural processes and for designing novel photonic materials. The aim of this review is to present an overview of the ab initio quantum chemical and time-dependent density functional theory methods that can be used to model spectroscopy and photochemistry in molecular systems. The applicability and limitations of the different methods as well as the main frontiers are discussed. To illustrate the progress achieved by excited-state chemistry in the recent years as well as the main challenges facing computational chemistry, three main applications that reflect the authors' experience are addressed: the UV/Vis spectroscopy of organic molecules, the assignment of absorption and emission bands of organometallic complexes, and finally, the obtainment of non-adiabatic photoinduced pathways mediated by conical intersections. In the latter case, special emphasis is put on the photochemistry of DNA. These applications show that the description of electronically excited states is a rewarding but challenging area of research.

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“…Four electronic transitions are expected, all of them active in one-photon spectroscopy, the two at lower energy denoted Q x , Q y while the two higher B x , B y coalesce in a single band (see Figure 48). A quantitative treatment of the vertical excitation energies for the three molecules can only be performed with ab initio calculation methods [297][298][299][300][301][302][303]. The results from three recent calculations relative to porphyrin and presented in Table 13 differ from experiment [299,304] by no more than 0.2 -0.3 eV not only for the Q x , Q y and B x , B y pairs but also for the weak transitions, usually denoted N x , N y and L y , and observed at higher energies with respect to the Soret band.…”

Section: Porphyrinsmentioning

confidence: 99%

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Gellini

Salvi

2010

Symmetry

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The paper introduces general considerations on structural properties of aromatic, antiaromatic and non-aromatic conjugated systems in terms of potential energy along bond length alternation and distortion coordinates, taking as examples benzene, cyclobutadiene and cyclooctatetraene. Pentalene, formally derived from cyclooctatetraene by cross linking, is also considered as a typical antiaromatic system. The main interest is concerned with [n]annulenes and model [n]annulene molecular systems, n ranging from 10 to 18. The rich variety of conformational and configurational isomers and of dynamical processes among them is described. Specific attention is devoted to bridged [10]-and [14]annulenes in the ground and lowest excited states as well as to s-indacene and biphenylene. Experimental data obtained from vibrational and electronic spectroscopies are discussed and compared with ab initio calculation results. Finally, porphyrin, tetraoxaporphyrin dication and diprotonated porphyrin are presented as annulene structures adopting planar/non-planar geometries depending on the steric hindrance in the inner macrocycle ring. Radiative and non-radiative relaxation processes from excited state levels have been observed by means of time-resolved fluorescence and femtosecond transient absorption spectroscopy. A short account is also given of porphycene, the structural isomer of porphyrin, and of porphycene properties.

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Excited and ionized states of free base porphin studied by the symmetry adapted cluster-configuration interaction (SAC-CI) method

Cited by 173 publications

References 47 publications

DFT/MRCI calculations on the excited states of porphyrin, hydroporphyrins, tetrazaporphyrins and metalloporphyrins

DFT/MRCI calculations on the excited states of porphyrin, hydroporphyrins, tetrazaporphyrins and metalloporphyrins

Progress and Challenges in the Calculation of Electronic Excited States

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

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