Diffusion Monte Carlo for fermions with replica reduction

Abstract

We propose an improved framework of diffusion Monte Carlo method for quantum many-fermion systems. This approach enables us to find the ground state of the system without any a priori information on the nodal structure of the wave function. The main idea in this approach is to use sign-carrying replicas which are the basis vectors in a restricted Hilbert space. For efficiency, we propose to reduce the number of replicas in a proper manner. We test our method on a spinless fermion system, and compare the results with the exact values. We also discuss this method in relation to exact diagonalization.