DFT-LDA PSEUDOPOTENTIALS IN QUANTUM MONTE-CARLO

We investigate the portability of standard norm-conserving pseudopoten tials outside the density functional theory-local density approximatio n (DET-LDA) framework, i.e., their use and interpretation as electron- ion effective potentials in valence-only diffusion Monte Carlo simulat ions. While first-principles many-body pseudopotentials are not availa ble in the literature yet, the use of approximate pseudopotentials in quantum Monte Carlo simulations is becoming widespread. Here we attemp t a systematic analysis of the portability of norm-conserving pseudopo tentials generated within DFT-LDA, focusing on a model many-body syste m, the two-electron valence-only ion. Our results indicate that the po rtability is good in most cases, hence the use of pseudopotentials in quantum Monte Carlo simulations is in general a reasonable approximati on but suggest that in some cases this approximation may be relevant. (C) 1997 John Wiley & Sons, Inc.