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Taffet, Elliot J.; Scholes, Gregory D.

doi:10.1016/j.chemphys.2017.12.008

Cited by 16 publications

(8 citation statements)

References 122 publications

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“…The counter-intuitive nuclear reorganization in S 2 from the crystal structure-a highly distorted peridinin conformationinvolves C=C contraction rather than elongation as we have reported previously for polyenes [47] and for peridinin [45] from an S 0 equilibrium geometry. Owing to intrinsic uncertainty in the protein crystal structure, it is unclear as to whether the geometric distortions in the 611N crystal-structure geometry are consequences of biological orientation or artefacts of extracting nuclear coordinates from a crystal structure.…”

Section: N Equilibrium-structure Resultssupporting

confidence: 63%

“…Our results stem from the application of multireference state-averaged complete-active-space self-consistent field royalsocietypublishing.org/journal/rsif J. R. Soc. Interface 17: 20190736 (CASSCF) and its approximate density-matrix-renormalization-group (DMRGSCF) form paired with second-order N-electron valence-state perturbation theory (NEVPT2)-an approach we have applied previously [45,47,48]-to capture the different electron-correlation types defining bright and dark states. Our optimal results from the best variational wave functions, tabulated in table 1 and graphically displayed in figure 1 for different active spaces, suggest that the S 1 and S 2 states are quasidegenerate for 611N in its crystal structure.…”

Section: N Crystal-structure Resultsmentioning

confidence: 99%

“…We have detailed our application of CASSCF/DMRGSCF and NEVPT2 in prior publications [45,47,48]. Briefly, we considered the variational quality of the wave functions computed across different active spaces by comparing variational CAS/DMRGSCF excitation energies with those after applying NEVPT2.…”

Section: Computational Detailsmentioning

confidence: 99%

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Uncovering dark multichromophoric states in Peridinin–Chlorophyll–Protein

Taffet

Fassioli

Toa

et al. 2020

J. R. Soc. Interface.

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It has long been recognized that visible light harvesting in Peridinin–Chlorophyll–Protein is driven by the interplay between the bright (S 2 ) and dark (S 1 ) states of peridinin (carotenoid), along with the lowest-lying bright (Q y ) and dark (Q x ) states of chlorophyll- a . Here, we analyse a chromophore cluster in the crystal structure of Peridinin–Chlorophyll–Protein, in particular, a peridinin–peridinin and a peridinin–chlorophyll- a dimer, and present quantum chemical evidence for excited states that exist beyond the confines of single peridinin and chlorophyll chromophores. These dark multichromophoric states, emanating from the intermolecular packing native to Peridinin–Chlorophyll–Protein, include a correlated triplet pair comprising neighbouring peridinin excitations and a charge-transfer interaction between peridinin and the adjacent chlorophyll- a . We surmise that such dark multichromophoric states may explain two spectral mysteries in light-harvesting pigments: the sub-200-fs singlet fission observed in carotenoid aggregates, and the sub-200-fs chlorophyll- a hole generation in Peridinin–Chlorophyll–Protein.

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Section: N Equilibrium-structure Resultssupporting

confidence: 63%

Section: N Crystal-structure Resultsmentioning

confidence: 99%

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Uncovering dark multichromophoric states in Peridinin–Chlorophyll–Protein

Taffet

Fassioli

Toa

et al. 2020

J. R. Soc. Interface.

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“…This mechanism is potentially matched by recent high-level calculations on polyenes. 99,100 These calculations identify a higher-lying B u state with similar spin entanglement to 2 1 A g but no binding energy and less mixing with other states. This state could effectively be 1 [T.T], suggesting the upper surface (B u character) has some parallel relaxation to 2 1 A g and B u -, which are electronically and spin-wise similar and located at comparable energies.…”

Section: Articlementioning

confidence: 81%

Optical Projection and Spatial Separation of Spin-Entangled Triplet Pairs from the S1 (21 Ag–) State of Pi-Conjugated Systems

Pandya

Cheminal

et al. 2020

Chem

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In quantum mechanics, entanglement is a powerful concept with applications in computing, cryptography, and chemical reactions to boost the efficiency of photovoltaic cells. An example of this in organic semiconductors is the coupling of localized triplet excitons into an overall spin-0, -1, or -2 configuration, termed the triplet-pair state. Here, we develop and apply methods to extract triplet pairs from the lowest excited singlet state in long conjugated molecules (polyenes) and understand the mechanism of this process for the aforementioned applications.

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“…trans -Butadiene is normally drawn with two conjugated double bonds, and its DVMS structure bears this out. Like for ethylene, accurate calculations for excited states of trans -butadiene require attention to correlation and basis set 20–23. The present wavefunctions were calculated at the (4,4) CAS-CI/6-31G(d) level, and we do not expect accurate energies or state-ordering.…”

Section: Resultsmentioning

confidence: 98%