THERMAL AND OPTICAL GAPS IN NEARLY-ONE-DIMENSIONAL COMPOUNDS

We discuss the consequences of the dispersion of the energy bands in t he broken symmetry (charge- and spin-density-wave) states of highly an isotropic metals. Such dispersion becomes important with increasing de viations from perfect nesting, and leads to differences between the ga ps as sampled by transport and optical measurements. We discuss the av ailable experimental results obtained in a variety of materials with d ifferent band-structure anisotropy.