  We theoretically investigate optical absorption of molecules embedded nearby
metallic antennas by using discrete dipole approximation method. It is found
that the spectral peak of the absorption is shifted due to the
radiation-induced correlation between the molecules. The most distinguishing
feature of our work is to show that the shift is largely enhanced even when the
individual molecules couple with localized surface plasmons near the different
antennas. Specifically, we first consider the case that two sets of dimeric
gold blocks with a spacing of a few nanometer are arranged, and reveal that the
intensity and spectral peak of the optical absorption strongly depends on the
position of the molecules. In addition, when the dimeric blocks and the
molecules are periodically arranged, the peak shift is found to increase up to
~1.2 meV (300 GHz). Because the radiation-induced correlation is essential for
collective photon emission, our result implies the possibility of
plasmon-assisted superfluorescence in designed antenna-molecule complex
systems.
