This renewal grant is for continuing work on density functional calculations of the electronic structure of high temperature superconductors. After nearly four years of intense study since the discovery of the high temperature superconductors, there is still no clear evidence of the mechanism that is responsible for their high transition temperatures. In light of recent experimental and theoretical studies, first principles theoretical calculations will be carried out on the electron-lattice coupling in order to assess the role played by this interaction in the high temperature superconductors. In these new materials unusual electron-lattice coupling may arise due to the presence of structural instabilities that are similar to those found in more conventional materials with related crystal structures. Investigation of such instabilities will therefore be undertaken. Computational techniques which will speed up these computationally- intensive calculations will also be explored.
