The structural optimization and normal-mode analysis are performed for the aryl ether azodendrimers on the basis of the semi-empirical molecular orbital methods. Through the geometrical characterization for the stable structures, the fractal dimension and the degree of azo core wrapping are found to provide key parameters related to the unique photoinduced isomerization. We also find that the normal-mode frequency distribution is virtually invariable irrespective of the molecular structure and generation of azodendrimers. The importance of normal-mode distribution gap in the range of 700-900 cm(-1) is suggested regarding the efficient vibrational energy transfer to the azo core region.