Single-Reference ab Initio Methods for the Calculation of Excited States of Large Molecules

Dreuw, Andreas; Head‐Gordon, Martin

doi:10.1021/cr0505627

Cited by 2,527 publications

(2,757 citation statements)

References 143 publications

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“…43,44,85 TDDFT, pure as well as hybrid, increasingly underestimates excitation energies of conjugated systems with increasing chain length. 42,45,46,[86][87][88] Since high level ab initio methods become prohibitively expensive for long chain cations, TDHF and TDDFT will be tested here for excited-state calculations on polyene cations.…”

Section: Methodsmentioning

confidence: 99%

Theoretical Investigation of Excited States of Large Polyene Cations as Model Systems for Lightly Doped Polyacetylene

Salzner

2006

J. Chem. Theory Comput.

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Electronic excitations of polyene cations with chain lengths of up to 101 CH units were investigated as model systems for lightly doped polyacetylene (PA). Since high level ab initio calculations such as complete active space perturbation theory (CASPT2) are limited to systems with about 14 CH units, the performances of time-dependent Hartree-Fock (TDHF) and time-dependent density functional theory (TDDFT) were evaluated. It turned out that TDDFT excitations energies are much more accurate for polyene cations than for neutral polyenes. The difference between TDHF and TDDFT excitation energies for the first allowed excited state of C 49 H 51 + is only 0.30 eV with pure DFT and 0.21 eV with a hybrid functional. For open-shell systems, pure DFT is found to be superior to DFT-hybrid functionals because it does not suffer from spin-contamination. Pure TDDFT excitation energies and oscillator strengths for small openshell polyene cations compare well with high level ab initio results. Excitation energies are found to be almost independent of the geometry, i.e., the size of the defect. Localization of the defect, however, shifts oscillator strengths from the HOMO-LUMO transition to higher lying excited states of the same symmetry. Lightly doped PA is predicted to exhibit several strong absorptions below 1 eV.

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Section: Methodsmentioning

confidence: 99%

Theoretical Investigation of Excited States of Large Polyene Cations as Model Systems for Lightly Doped Polyacetylene

Salzner

2006

J. Chem. Theory Comput.

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“…The equilibrium structures of D35 (S 0 ) and D35 + (D 0 ) were optimized using the B3LYP functional 30 and a 6-31G(d) basis set. Time-dependent density functional theory (TDDFT) 31,32 was applied to these geometries for calculating the lowest 5 singlet (neutral D35) and lowest 20 doublet (D35 + ) excited electronic states at vertical excitation using MPW1K 33 and B3LYP functionals in combination with a 6-31+G(d) basis set. Calculations were carried out using the Gaussian 09 package.…”

Section: Calculationsmentioning

confidence: 99%

Photoinduced ultrafast dynamics of the triphenylamine-based organic sensitizer D35 on TiO2, ZrO2 and in acetonitrile

Oum

Lohse

Klein

et al. 2013

Phys. Chem. Chem. Phys.

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The relaxation dynamics of the dye D35 has been characterized by transient absorption spectroscopy in acetonitrile and on TiO 2 and ZrO 2 thin films. In acetonitrile, upon photoexcitation of the dye via the S 0 -S 1 transition, we observed ultrafast solvation dynamics with subpicosecond time constants.Subsequent decay of the S 1 excited state absorption (ESA) band with a 7.1 ps time constant is tentatively assigned to structural relaxation in the excited state, and a spectral decay with 203 ps time constant results from internal conversion (IC) back to S 0 . On TiO 2 , we observed fast (o90 fs) electron injection from the S 1 state of D35 into the TiO 2 conduction band, followed by a biphasic dynamics arising from changes in a transient Stark field at the interface, with time constants of 0.8 and 12 ps, resulting in a characteristic blue-shift of the S 0 -S 1 absorption band. Several processes can contribute to this spectral shift: (i) photoexcitation induces immediate formation of D35 + radical cations, which initially form electron-cation complexes; (ii) dissociation of these complexes generates mobile electrons, and when they start diffusing in the mesoporous TiO 2 , the local electrostatic field may change; (iii) this may trigger the reorientation of D35 molecules in the changing electric field. A slower spectral decay on a nanosecond timescale is interpreted as a reduction of the local Stark field, as mobile electrons move deeper into TiO 2 and are progressively screened. Multiexponential electron-cation recombination occurs on much longer timescales, with time constants of 30 ms, 170 ms and 1.4 ms. For D35 adsorbed on ZrO 2 , there is no clear evidence for a transient Stark shift, which suggests that initially formed cation-electron (trap state) complexes do not dissociate to form mobile conduction band electrons.Multiexponential decay with time constants of 4, 35, and 550 ps is assigned to recombination between cations and trapped electrons, and also to a fraction of D35 molecules in S 1 which decay by IC to S 0 .Differential steady-state absorption spectra of D35 + in acetonitrile and dichloromethane provide access to the complete D 0 -D 1 band. The absorption spectra of D35 and D35 + are well described by TDDFT calculations employing the MPW1K functional.

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“…In fact, this presents another justification of the hybrid scheme to obtain the correct excited state curve by combining both DFT and CIS results. 8,11 However, the situation will change at short R. The error of CIS is due to the difference in the correlations on the ground and the excited electronic states. (Namely, if the correlations are the same on the two states, CIS will give the correct result.)…”

Section: Ss U C Even Though the Reduced Error Is A Desirable Feature mentioning

confidence: 99%

“…Despite its low cost mean-field level computational effort (formally scaling ~N 4 or better with respect to the system size N), TDDFT has been shown to be reliable for many chemically interesting systems. 8 However, it has a serious failure in the description of an important class of excitations. 11 TDDFT calculations must use an approximation for the exchange-correlation (xc) functional, and no xc-functional at present is known to be efficient, reliable for various systems and free from the self-interaction-error.…”

Section: Introductionmentioning

confidence: 99%

Scaled Second-Order Perturbation Corrections to Configuration Interaction Singles: Efficient and Reliable Excitation Energy Methods

2007

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Single-Reference ab Initio Methods for the Calculation of Excited States of Large Molecules

Cited by 2,527 publications

References 143 publications

Theoretical Investigation of Excited States of Large Polyene Cations as Model Systems for Lightly Doped Polyacetylene

Theoretical Investigation of Excited States of Large Polyene Cations as Model Systems for Lightly Doped Polyacetylene

Photoinduced ultrafast dynamics of the triphenylamine-based organic sensitizer D35 on TiO2, ZrO2 and in acetonitrile

Scaled Second-Order Perturbation Corrections to Configuration Interaction Singles: Efficient and Reliable Excitation Energy Methods

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