On the origin of matrix elements for electronic excitation (energy) transfer

Abstract

Configuration interaction and the theory of electronic factors in energy transfer and molecular exciton interactionsStructure of complex systems using electronic excitation transport: Theory, Monte Carlo simulations, and experiments on micelle solutions Electronic excitation transfer in clustered chromophore systems: Calculation of timeresolved observables for intercluster transferThe origin of electronic energy transfer ͑EET͒ between two chromophores ͑D and A͒ is explored further for several molecular situations that may be encountered in experiment-namely, nonoverlapping active-space orbitals of the D and A chromophores, forbidden electronic excitations for both chromophores, and an allowed and a forbidden electronic excitation for the D and A chromophores, respectively. The theory is illustrated via the results of calculations of the EET matrix elements for model systems with both four-eight active-space electrons and all of the electrons included explicitly. In each case, it is found that any overlap contribution to these matrix elements is associated much more with charge-transfer and penetration terms rather than it is with the Dexter exchange integral. The calculated magnitude of the latter integral is always smaller than that of the Coulomb integral.

Exciton mobility control throughsub−Åpacking modifications in molecular crystals

“…Coulombic coupling. [24][25][26] For TAT, our calculations reveal a screened n.n. Coulomb coupling of approximately 300-400 cm -1 which is compensated by a short-range coupling of comparable magnitude but opposite sign.…”

Theory of excitation energy transfer: from structure to function

“…This short-range coupling further red-shifts the excited state energies (Warshel and Parson 1987). The origin of this additional shift is on one hand a short-range contribution to the excitonic coupling, first proposed by Dexter (1953), and on the other hand a coupling between the exciton states and intramolecular charge transfer states (Harcourt et al 1996) that shifts the local transition energies of the pigments and also contributes to the excitonic coupling. In antenna systems, these electron exchange effects are much smaller, a notably exception being the red antenna states of photosystem I.…”

Quantum Chemical Description of Absorption Properties and Excited‐State Processes in Photosynthetic Systems

“…[158,232,255,265] This even holds if one or both interacting monomer transitions are dipole forbidden. [266] However, Madjet et al noted that in the case of a special pair (see Section 6.5.1), the short-range contributions may not be neglected. It was speculated that in earlier calculations of the spectra without this contribution, the overall good results may be caused by an overestimation of the Coulombic interaction.…”