Charge density waves in layered compounds

The metallic layered compounds of the transition metal dichalcogenide type show unusual deviations from simple metallic behavior. These deviations are due to Charge Density Wave instabilities that are driven by the Fermi surface. The Charge Density Wave is a coupled periodic distortion of the conduction electron density and the crystal lattice. The effects of the CDW on the physical properties are qualitatively discussed. The basic driving forces of the CDW are most likely responsible for structural changes in a wide variety of materials, such as high temperature superconductors and long period superlattice alloys.