PARQUET APPROXIMATION FOR A DISORDERED 2-DIMENSIONAL ELECTRON-GAS IN A STRONG TRANSVERSE MAGNETIC-FIELD

The density of states and the diagonal magnetoconductivity of a disord ered two-dimensional electron gas under quantizing magnetic fields is treated in the parquet approximation. Results for the lowest Landau su bband are obtained by considering the lowest-order irreducible vertex diagrams. An analytical solution is derived for a self-consistent appr oximation, which includes both particle-particle and particle-hole lad der diagrams. The parquet density of states agrees quite well with the exact result obtained by F Wegner. The dependence on a short-range pa rameter is discussed. The diagonal magnetoconductivity is calculated i n various approximations and the results are compared with each other. Possibilities to improve the calculation of the magnetoconductivity a re discussed.