This is a renewal grant for a theoretical program studying the structure and excitations of low dimensional systems. The systems studied in this program are quasi-one-and-two dimensional systems including the conducting polymers, two dimensional strongly correlated lattice fermion systems relevant to the superconducting oxides, the organic charge transfer salts, and the alkalides which represent a new class of synthetic Mott insulators. We will explore the low energy physics in these systems which leads to structures with broken translational symmetry, and particularly phenomena which can lead to modulated or incommensurate structures in the ground state. The structure of these novel states of matter and their low lying excitations will be studied.//
