Dynamic structure factor of a two-dimensional electron gas

The dynamic structure factor S(k,{ω}) of a two-dimensional electron gas is calculated at rₛ=1 and 5 within the Mori memory function formalism. We use the Gaussian model for the memory function at second stage and obtain the necessary static inputs from the quantum Monte Carlo calculation by Tanatar and Ceperley and Moroni, Ceperley, and Senatore. S(k,{ω}) thus calculated shows a clear two-peak structure in the intermediate wave-vector domain beyond the plasmon cutoff wave vector at both rₛ=1 and 5. The results are compared with the quantum Singwi-Tosi-Land-Sj\"olander (QSTLS) theory and the calculation of Tanatar. It is found that our results are similar to that of QSTLS at rₛ=5 and do not support the Tanatar prediction of finding only a single broad peak at intermediate k. {} 1996 The American Physical Society.