setup_delta_psi Subroutine

    subroutine setup_delta_psi()
        ! temp_det_list is sufficient as a cache
        ! note that therefore, dpsi_cache also has a hashtable (temp_det_hash)
        dpsi_cache => temp_det_list
        max_cache_size = size(WalkVecDets, dim=2)
    end subroutine setup_delta_psi