OPTIMIZED WAVE-FUNCTIONS FOR QUANTUM MONTE-CARLO STUDIES OF ATOMS ANDSOLIDS

Wave functions for the homogeneous electron gas, a germanium pseudosol id, and a germanium pseudoatom are optimized using the method of varia nce minimization. Forms for the Jastrow factor which are convenient to optimize and may be evaluated rapidly are devised and tested and we s tress the advantages of using expressions which are linear in the vari able parameters. For each system studied we have performed variational and diffusion quantum Monte Carlo calculations to test the accuracy o f the optimized wave functions. The results of our study are very prom ising for future applications of quantum Monte Carlo methods to real m aterials.