(a)  Experimental Results
(b) Calculated Results
Figure 1: (a) Experimental results for the highest and branch of for various doping levels [6]. : , : , : , : . The lines are a guide to the eye. (b) Calculated results of the phonon branches shown in (a) as obtained with our model approach for the electronic state of the HTSCs [1]. : insulating state, : underdoped state, − − −: optimally doped state, : overdoped state. For comparison, the results for the RIM are shown in order to demonstrate the crucial influence of the nonlocal EPI effects in form of CFs on the dispersion.