Adiabatic exciton states

In contrast to Eq. (14) introducing ordinary exciton states, adiabatic exciton states are defined as the instantaneous eigenstates of the singly excited CC, i.e. they are obtained by diagonalizing Vmn, Eq. (10). The states can be expanded according to... 

Fig. 8 shows respective simulation results. The estimate using adiabatic exciton states (see the subsequent section) coincides with the LRT absorbance. Although the electrostatic coupling to solvent molecules has been included the achieved broadening is insufficient to meet the measured curve. An additional broadening due to the inclusion of intra chromophore vibrations removes this discrepancy. 

Estimate of the Absorbance Using Adiabatic Exciton States... 

Adiabatic exciton states have been introduced in Section 2.5. They are used to arrive at the following approximate formula for the CC absorption cross section [9] ... 

In contrast, the exciton-polaron (l B. )) state is expected to be in the adiabatic limit, as its energy in the undimerized Pariser-Parr-Pople model is 1.6 eV in the long chain limit. This is confirmed by Fig. 10.7, which show the deviations between the quantum and adiabatic limits is only ca. 0.1 eV at 102 sites. 

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