Effect of exchange on charge density waves in layered compounds

The first-order (exchange) correction π1(q) to the static polarizability of an interacting two-dimensional electron gas is calculated numerically, and is found to be sharply peaked at q=2kF. An estimate of the magnitude of this correction in metallic layered compounds shows that the exchange enhancement of the polarizability is comparable to the band structure enhancement. Exchange and correlation therefore play an important role in the charge density wave instabilities observed in these compounds. © 1978.