CORRELATION-ENERGY OF A 2-DIMENSIONAL ELECTRON-GAS

Extending the Hedin-Lundqvist approximation, originally developed for the three-dimensional electron gas, we derive the correlation energy E (c) for the two-dimensional electron gas as a function of electron den sity rho. A simple two-parameter function E(c)(rho) reproduces very we ll the first-principles numerical results in the whole density range. We also present a simple and accurate form of the correlation part of the chemical potential, which can be used, e.g., as a correlation part of the effective potential in the local-density approximation for two -dimensional electron systems.