Symmetry adapted basis defect patterns for analysis of the effects of energy disorder on cyclic arrays of coupled chromophores Original Research Article

The effects of diagonal and off-diagonal energy disorder on the exciton level structure and spectroscopic properties of cyclic (Cn) arrays of coupled chromophores are analyzed using symmetry adapted basis defect patterns (BDP). An important aspects of this approach is that any arbitrary defect pattern can be expressed as a superposition of BDP. Determination of the effects of each BDP on the exciton manifold allows for a systematic approach to the question of whether or not energy disorder can account for spectroscopic data given a zero-order Cn-Hamiltonian. The insights provided by representation theory and the BDP are illustrated with an application to a C9-ring of bacteriochlorophyll molecules such as found in light harvesting complex 2 of purple bacteria. An understanding of how energy disorder affects exciton level structure is essential for understanding inter-exciton level relaxation dynamics.