Many-body diffusion algorithm: Harmonic fermions

A numerical implementation scheme is presented for the recently developed many-body diffusion approach for identical particles, in the case of harmonic potentials. The procedure is free of the sign problem, by the introduction of the appropriate absorption or reflection conditions for the walkers at the boundary of a state space. These conditions are imposed by the permutation symmetry. The outflow of the walkers at the boundary of the state space contributes substantially to the energy. Furthermore, the implementation of crossing/recrossing effects at absorbing boundaries proves indispensable to sample the antisymmetric states by discrete time steps.