DYNAMIC STRUCTURE FACTOR OF A 2-DIMENSIONAL ELECTRON-GAS

The dynamic structure factor S(k, omega) of a two-dimensional electron gas is calculated at r(s) = 1 and 5 within the Mori memory function f ormalism. We use the Gaussian model for the memory function at second stage and obtain the necessary static inputs from the quantum Monte Ca rlo calculation by Tanatar and Ceperley and Moroni, Ceperley, and Sena tore. S(k, omega) thus calculated shows a clear two-peak structure in the intermediate wave-vector domain beyond the plasmon cutoff wave vec tor at both r(s) = 1 and 5. The results are compared with the quantum Singwi-Tosi-Land-Sjolander (QSTLS) theory and the calculation of Tanat ar. It is found that our results are similar to that of QSTLS at r(s) = 5 and do not support the Tanatar prediction of finding only a single broad peak at intermediate k.