Phenylacetylene-based molecules studied: (a) linear chains, (b) meta- and (c) orthosubstituted two-segment molecules denoted by , , and , respectively; (d) definition of one repeat unit.
Examples of transition density matrices for the light (a) and heavy (b) excitons in the linear molecule P10 of ten repeat units. Joint electron-hole motion is similar in these modes: both excitations are the second states in the respective excitonic bands, and their standing waves have one node.
Dispersions of two lowest-energy excitons in phenylacetylene oligomers, the light (squares) and heavy (filled circles) excitons. The light-exciton dispersion is approximated by one cosine (dashed line, the parameters are , ) and three cosine harmonics (solid line, the parameters are , , , and ).
Scattering phases: at the molecular terminals, (solid black line); at the orthosubstituted linkages, and (red dashed and dotted lines); at the metasubstituted linkages, and (blue dashed and dotted lines).
Deviations between the CEO excitation energies in the linear molecules and the smooth dispersion of the ES model: (a) all states and (b) a zoomed in view (note that the numerical accuracy of the CEO method was estimated as 0.01 meV). The mode in the molecule is denoted by .
Difference between the ES and CEO results for excitation energies in selected (a) meta- and (b) orthoconjugated molecules. stands for an X-conjugated molecule ( or ) that consists of two segments with and repeat units.
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