Methods of Fermion Monte Carlo

This talk will outline Monte Carlo methods that enable numerical solution of the mony-body non-relativistic Schroedinger equation. They permit computations with no uncontrolled approximations for the ground state of bosonic systems. Extension to fermionic systems has proved much more difficult. The algorithmic barriers will be outlined, together with techniqDues that overcome them. The latter include the use of populations of pairs of random walkers that carry opposite algebraic signs; the corelation of their diffusion paths; cancellation of pairs that become close.; the use of different permutations to achieve statistical stability; and importance sampling. Results for the two-dimensional electron gas will be presented.