MANY-ELECTRON CORRELATED EXPONENTIAL WAVE-FUNCTIONS - A QUANTUM MONTE-CARLO APPLICATION TO H-2 AND HE-2(+)

We propose to expand the solution of the Schrodinger equation for an atomic or molecular system as a linear combination of many-electron explicitly correlated exponentials. A series of trial wavefunctions has been optimized, minimizing the variance of the local energy for H-2 and He-2(+) in their ground state at the equilibrium distance, and their variational energy has been computed using the variational Monte Carlo method. The He-2(+) wavefunctions have been used in a series of fixed node diffusion Monte Carlo simulations, showing that, using a small number of terms, one can obtain a good estimate of the exact energy.