Coupling of charge-transfer excitons, Frenkel excitons, and vibrations in a two-dimensional quadratic lattice

Abstract

The paper offers a theoretical model of Frenkel and charge-transfer excitons coupling in a two-dimensional quadratic lattice. This coupling manifests a strong anisotropy in the plane of the lattice and perpendicular to it. The paper contains symmetry analysis of Frenkel and charge-transfer excitons coupling for the two cases. The spectra of the linear absorption in the excitonic and vibronic regions with one and two quanta of intramolecular vibration have been calculated by using the Green functions formalism and the vibronic approach. The numerical simulations demonstrate peculiarities of the excitonic density of states and of the spectra of linear absorption in the excitonic region, as well as in vibronic spectra inside the bands of many-particle states and near the levels of the bound (one-particle) exciton–phonon states.