The effect of anisotropy on the absorption spectrum and the density of states of two-dimensional Frenkel exciton systems with Gaussian diagonal disorder

TL;DR

This paper investigates how anisotropy influences the optical absorption and density of states in two-dimensional Frenkel exciton systems with Gaussian disorder, revealing that anisotropy significantly affects the density of states but only weakly impacts absorption.

Contribution

It introduces an elliptic integral approach to analyze the entire spectrum and demonstrates the utility of the coherent potential approximation for interpreting optical properties in these systems.

Findings

Absorption is weakly affected by anisotropy.

Density of states shows strong anisotropic effects.

Results align with previous finite array calculations.

Abstract

On the optical absorption and the density of states of Frenkel exciton systems on square, rectangular, and triangular lattices with nearest-neighbor interactions and a Gaussian distribution of transition frequencies. The analysis is based on an elliptic integral approach that gives results over the entire spectrum. It is found that the absorption is weakly affected by the anisotropy in contrast to the density of states where the effects can be much stronger. The results for the square lattice are in good agreement with the finite array calculations of Schreiber and Toyozawa. Our findings suggest that the coherent potential approximation can be useful in interpreting the optical properties of two-dimensional systems with dominant nearest-neighbor interactions and Gaussian diagonal disorder where the optically excited states are Frenkel excitons.