9404954 This is a renewal grant which focuses on calculating the electronic structure of the high temperature superconductors in order to assess the role of the electron-phonon interaction. First principles calculations will be done using a newly developed linearized augmented plane wave linear response method. Some of the work will be done in collaboration with the theory group at the Naval Research Laboratory. %%% Calculations will be done to determine properties of the high temperature superconductors. The results of this work will not only help us understand the basic structure of these materials, but it may shed light on the underlying mechanisms which cause these insulating materials to become superconductors.