Time-Dependent Density Functional Study of the Electronic Excited States of Polycyclic Aromatic Hydrocarbon Radical Ions

Hirata, So; Head‐Gordon, Martin; Szczepański, Jan; Vala, Martin

doi:10.1021/jp0301913

Cited by 102 publications

(132 citation statements)

References 72 publications

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“…This includes the broad absorption peak dominated by σ * ← σ transitions, which matches well both in position and width. Concerning the low-lying excited states of π * ← π character occurring in the near-IR, visible, and near-UV spectral ranges, the computed vertical excitation energies are precise to within a few tenths of eV (in the range 0.1−0.4 eV), which are indeed the typical accuracies achievable by TD-DFT using hybrid or gradient-corrected exchange-correlation functionals (Hirata et al 1999(Hirata et al , 2003. We proved these data to be reliable enough for detailed modelling of PAHs in different charge states when laboratory data are missing (Mulas et al 2006a,b,c).…”

Section: ++supporting

confidence: 57%

“…Hybrid DFT functionals are a little more expensive than other exchange-correlation functionals but yield better results. The B3LYP functional, in particular, is widely used in the study of PAHs and related species (Martin et al 1996;Langhoff 1996;Wiberg 1997;Bauschlicher & Langhoff 1997;Kato et al 1999;Kato & Yamabe 2002;Dessent 2000;Bauschlicher & Bakes 2000Schröder et al 2001;Rienstra-Kiracofe et al 2001;Bauschlicher 2002;Hirata et al 2003;Deleuze et al 2003;Rosi et al 2004;Woon & Park 2004;Jolibois et al 2005;Witt et al 2006;Kadantsev et al 2006). To assess the impact of this choice we also considered some more recently developed functionals, such as the so-called B−97 (Becke 1997) and HCTH (Hamprecht et al 1998), but no significant improvements, if any, were obtained with respect to B3LYP for calculating the ionisation energies of PAHs.…”

Section: Ionisation Energies and Vibrational Propertiesmentioning

confidence: 99%

“…In this scheme, computational costs scale steeply with the number of required transitions, and the excitation spectra are limited to the low-energy part of the spectrum (e.g., Hirata et al 1999Hirata et al , 2003. The advantages of the real-time propagation method used here are discussed by Lopez et al (2005).…”

Section: ++mentioning

confidence: 99%

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Theoretical evaluation of PAH dication properties

Malloci

Joblin

Mulas

2006

A&A

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Aims. We present a systematic, theoretical study of 40 polycyclic aromatic hydrocarbon dications (PAHs ++ ) containing up to 66 carbon atoms. Methods. We performed our calculations using well-established quantum-chemical techniques in the framework of (i) the density functional theory (DFT) to obtain the electronic ground-state properties and of (ii) the time-dependent DFT (TD-DFT) to evaluate the excited-state properties. Results. For each PAH++ considered, we computed the absolute visible-UV photo-absorption cross-section up to about 30 eV. We also evaluated their vibrational properties and compared them to those of the corresponding neutral and singly-ionised species. We estimated the adiabatic and vertical second ionisation energy ∆I through total energy differences. Conclusions. The ∆I values obtained fall in the energy range 8−13 eV, confirming that PAHs could reach the doubly-ionised state in HI regions. The total integrated IR absorption cross-sections show a marked increase upon ionisation, being on the average about two and five times larger for PAHs ++ than for PAHs + and PAHs, respectively. The visible-UV photo-absorption cross-sections for the 0, +1 and +2 charge-states show comparable features but PAHs ++ are found to absorb slightly less than their parent neutral and singly ionised species between ∼7 and ∼12 eV. Combining these pieces of information, we found that PAHs ++ should actually be stabler against photodissociation than PAHs and PAHs + , if dissociation thresholds are nearly unchanged by ionisation.

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Section: ++supporting

confidence: 57%

Section: Ionisation Energies and Vibrational Propertiesmentioning

confidence: 99%

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Theoretical evaluation of PAH dication properties

Malloci

Joblin

Mulas

2006

A&A

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“…A range separated density functional, ωB97 (Chai & Head-Gordon 2008), that is specifically designed for weak interactions was also employed. For valence electronic transitions TDDFT has been shown to work well (Hirata et al 1999;Weisman et al 2001;Halasinski et al 2003;Hirata et al 2003). The range-separated functional, ωB97, significantly reduces the serious problems of TDDFT with conventional functionals for charge-transfer excited states (Dreuw & Head-Gordon 2004).…”

Section: Theoretical Methodsmentioning

confidence: 99%

Initiating molecular growth in the interstellar medium via dimeric complexes of observed ions and molecules

Bera

Head‐Gordon

Lee

2011

A&A

Self Cite

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A feasible initiation step for particle growth in the interstellar medium (ISM) is simulated by means of ab initio quantum chemistry methods. The systems studied are dimer ions formed by pairing nitrogen containing small molecules known to exist in the ISM with ions of unsaturated hydrocarbons or vice versa. Complexation energies, structures of ensuing complexes and electronic excitation spectra of the encounter complexes are estimated using various quantum chemistry methods. Møller-Plesset perturbation theory (MP2), Z-averaged perturbation theory (ZAPT2), coupled cluster singles and doubles with perturbative triples corrections (CCSD(T)), and density functional theory (DFT) methods (B3LYP) were employed along with the correlation consistent cc-pVTZ and aug-cc-pVTZ basis sets. Two types of complexes are predicted. One type of complex has electrostatic binding with moderate (7−20 kcal mol −1 ) binding energies, that are nonetheless significantly stronger than typical van der Waals interactions between molecules of this size. The other type of complex develops strong covalent bonds between the fragments. Cyclic isomers of the nitrogen containing complexes are produced very easily by ion-molecule reactions. Some of these complexes show intense ultravioletvisible spectra for electronic transitions with large oscillator strengths at the B3LYP, ωB97, and equations of motion coupled cluster (EOM-CCSD) levels. The open shell nitrogen containing carbonaceous complexes especially exhibit a large oscillator strength electronic transition in the visible region of the electromagnetic spectrum.

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“…4 Here we have used a wider range of basis sets, including the cc-pVDZ and cc-pVTZ basis sets for water and 6-31G, cc-pVDZ, and cc-pVTZ basis sets for nitrogen. 34,35 For assessment, we carried out calculations with state-of-the-art internally contracted multireference methods-second-and third-order perturbation theory ͑CASPT2 and CASPT3͒, [36][37][38][39] configuration interaction ͑MR-CI͒, 40-42 the a posteriori size-extensivity corrected configuration interaction due to Davidson ͑MR-CI+ Q͒, 43,44 averaged coupled pair functional ͑MR-ACPF͒, 45,46 and averaged quadratic coupled cluster theory 47 ͑MR-AQCC͒ ͑both a priori size-extensivity modifications of configuration interaction͒, as well as single-reference coupled cluster calculations at the CCSD and CCSDT level 48,49 ͒. Full configuration interaction ͑FCI͒ energies were also used for comparison where available.…”

Section: Calculations a Water And Nitrogen Potential Energy Curvesmentioning

confidence: 99%

Canonical transformation theory from extended normal ordering

Yanai

Chan

2007

The Journal of Chemical Physics

135

156

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The canonical transformation theory of Yanai and Chan ͓J. Chem. Phys. 124, 194106 ͑2006͔͒ provides a rigorously size-extensive description of dynamical correlation in multireference problems. Here we describe a new formulation of the theory based on the extended normal ordering procedure of Mukherjee and Kutzelnigg ͓J. Chem. Phys. 107, 432 ͑1997͔͒. On studies of the water, nitrogen, and iron oxide potential energy curves, the linearized canonical transformation singles and doubles theory is competitive in accuracy with some of the best multireference methods, such as the multireference averaged coupled pair functional, while computational timings ͑in the case of the iron oxide molecule͒ are two to three orders of magnitude faster and comparable to those of the complete active space second-order perturbation theory. The results presented here are greatly improved both in accuracy and in cost over our earlier study as the result of a new numerical algorithm for solving the amplitude equations.

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Time-Dependent Density Functional Study of the Electronic Excited States of Polycyclic Aromatic Hydrocarbon Radical Ions

Cited by 102 publications

References 72 publications

Theoretical evaluation of PAH dication properties

Theoretical evaluation of PAH dication properties

Initiating molecular growth in the interstellar medium via dimeric complexes of observed ions and molecules

Canonical transformation theory from extended normal ordering

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