Conical for Stepwise, Glancing for Concerted: The Role of the Excited-State Topology in the Three-Body Dissociation of <i>sym</i>-Triazine

Mozhayskiy, Vadim A.; Savee, John David; Mann, Jennifer E.; Continetti, Robert E.; Krylov, Anna I.

doi:10.1021/jp806369s

Cited by 17 publications

(46 citation statements)

References 57 publications

(106 reference statements)

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“…1,2 There are about 30 systems that were characterized to be capable of three-body photodissociation up to date. Dynamic information of two-body decay can be obtained through straightforward experiments.…”

Section: Introductionmentioning

confidence: 99%

“…However, the acquisition of dynamic information for photoinitiated three-body processes has proven to be a challenge for theoreticians and experimentalists alike, due to the inherent difficulties in predicting behavior of excited molecules and in directly observing multiple dissociation products. [1][2][3] The photodissociation of phosgene ͑Cl 2 CO͒ has received considerable attention in the past decades, since it is an excellent model molecule for studying three-body dissociation dynamics. 2,3 However, there is a history of controversy over whether the photoinitiated three-body dissociation proceeds in a stepwise or a concerted fashion for almost every one of these systems, such as CH 3 COCH 3 , 3,4 SOCl 2 , 3,5,6 CH 2 XCH 2 Y ͑X , Y =Br,Cl͒, 7,8 C 3 N 3 H 3 ͑s-triazine͒, 1,2 C 2 N 4 H 2 ͑s-tetrazine͒, 9 and phosgene ͑Cl 2 CO͒.…”

Section: Introductionmentioning

confidence: 99%

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Photodissociation of phosgene: Theoretical evidence for the ultrafast and synchronous concerted three-body process

Qiu

Zhang

Shen

et al. 2009

The Journal of Chemical Physics

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The potential energy surfaces for Cl(2)CO dissociation into CO+Cl+Cl in the lowest two electronic singlet states (S(0) and S(1)) have been determined by the complete active space self-consistent field, coupled-cluster method with single and double excitations (CCSD), and equation-of-motion CCSD calculations, which are followed by direct ab initio molecular dynamics simulations to explore its photodissociation dynamics at 230 nm. It is found that the C-O stretching mode is initially excited upon irradiation and the excess internal energies are transferred to the C-Cl symmetric stretching mode within 200 fs. On average, the first and the second C-Cl bonds break completely within subsequent 60 and 100 fs, respectively. Electronic structure and dynamics calculations have thus provided a strong evidence that the photoinitiated dissociation of Cl(2)CO at 230 nm or shorter wavelengths is an ultrafast, adiabatic, and concerted three-body process. Since the two C-Cl bonds begin to break at the same time and the time interval between the two C-Cl bond broken fully is very short ( approximately 40 fs), the photoinitiated dissociation of Cl(2)CO to CO+2Cl can be considered as the synchronous concerted process.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photodissociation of phosgene: Theoretical evidence for the ultrafast and synchronous concerted three-body process

Qiu

Zhang

Shen

et al. 2009

The Journal of Chemical Physics

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“…Theoretical methods: EOM-CC methods for interacting states of different nature Although the original applications of the EOM formalism were concerned mostly with accurate energy difference calculations, i.e. excitation and IEs, the full potential of EOM as a tool for interacting electronic states of different nature has only been exploited more recently [13,[61][62][63][64][65][66][67][68].…”

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confidence: 99%

Interacting Rydberg and valence states in radicals and molecules: experimental and theoretical studies

Reisler

Krylov

2009

International Reviews in Physical Chemistry

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105

125

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This review discusses low-lying (n ¼ 3) Rydberg electronic states of molecules and radicals, in particular those that result in mixed configurations and participate in non-adiabatic interactions. Rydberg-valence interactions are ubiquitous in molecules and radicals and have important effects on potential energy surface shapes, spectroscopy, and dissociation dynamics. The review emphasises selected properties that are affected by these interactions and illustrates them with several examples, mostly involving free radicals, in which collaboration between experimental and theoretical investigations has been crucial for understanding. Specifically, the cases of substituted methyl, vinyl, and hydroxyalkyl radicals are described, as well as Rydberg states of diazomethane and the ethyl radical. The issue of triple conical intersections is also briefly discussed.

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“…Thus, EOM-CC is an attractive platform for computing MECPs and NACs. [55][56][57][58][59][60][61][62] Formulation of NACs within EOM-CC theory have been described for EE (excitation energy) and IP (ionization potential) variants. 14,55 Here we extend the theory by including the EOM-EA (EOM for electron affinity) method.…”

Section: Introductionmentioning

confidence: 99%

Calculations of non-adiabatic couplings within equation-of-motion coupled-cluster framework: Theory, implementation, and validation against multi-reference methods

Faraji

Matsika

Krylov

2018

The Journal of Chemical Physics

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We report an implementation of non-adiabatic coupling (NAC) forces within the equation-of-motion coupled-cluster with single and double excitations (EOM-CCSD) framework via the summed-state approach. Using illustrative examples, we compare NAC forces computed with EOM-CCSD and multi-reference (MR) wave functions (for selected cases, we also consider configuration interaction singles). In addition to the magnitude of the NAC vectors, we analyze their direction, which is important for the calculations of the rate of non-adiabatic transitions. Our benchmark set comprises three doublet radical-cations (hexatriene, cyclohexadiene, and uracil), neutral uracil, and sodium-doped ammonia clusters. When the characters of the states agree among different methods, we observe good agreement between the respective NAC vectors, both in the Franck-Condon region and away. In the cases of large discrepancies between the methods, the disagreement can be attributed to the difference in the states' character, which, in some cases, is very sensitive to electron correlation, both within single-reference and multi-reference frameworks. The numeric results confirm that the accuracy of NAC vectors depends critically on the quality of the underlying wave functions. Within their domain of applicability, EOM-CC methods provide a viable alternative to MR approaches.

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Conical for Stepwise, Glancing for Concerted: The Role of the Excited-State Topology in the Three-Body Dissociation of sym-Triazine

Cited by 17 publications

References 57 publications

Photodissociation of phosgene: Theoretical evidence for the ultrafast and synchronous concerted three-body process

Photodissociation of phosgene: Theoretical evidence for the ultrafast and synchronous concerted three-body process

Interacting Rydberg and valence states in radicals and molecules: experimental and theoretical studies

Calculations of non-adiabatic couplings within equation-of-motion coupled-cluster framework: Theory, implementation, and validation against multi-reference methods

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