EFFECTS OF BACKFLOW CORRELATION IN THE 3-DIMENSIONAL ELECTRON-GAS - QUANTUM MONTE-CARLO STUDY

The correlation energy of the homogeneous three-dimensional interactin g electron gas is calculated using the variational and fixed-node diff usion Monte Carlo methods, with trial functions that include backflow and three-body correlations. In the high-density regime (r(s)less than or equal to 5) the effects of backflow dominate over those due to thr ee-body correlations, but the relative importance of the latter increa ses as the density decreases. Since the backflow correlations vary the nodes of the trial function, this leads to improved energies in the f ixed-node diffusion Monte Carlo calculations. The effects are comparab le to those found for the two-dimensional electron gas, leading to muc h improved variational energies and fixed-node diffusion energies simi lar to the released-node energies of Ceperley and Alder.