create_perturbed_ref Subroutine

    subroutine create_perturbed_ref(perturbed_buf, tmp_totwalkers)
        implicit none
        integer(n_int), intent(out) :: perturbed_buf(:, :)
        integer, intent(out) :: tmp_totwalkers

        integer :: nPertRefs
        integer(n_int) :: tmpRef(0:NIfTot, 1)
        character(*), parameter :: t_r = "create_perturbed_reference"

        ! create a perturbed reference determinant as overlap state
        nPertRefs = 0
        ! i.e. take the most populated determinant (over all procs)
        call generate_space_most_populated(1, .false., 1, tmpRef, nPertRefs, &
                                           GLOBAL_RUN, perturbed_buf, int(tmp_totwalkers, n_int))

        ! from now on, we treat the perturbed_buf as 1-sized
        perturbed_buf = 0
        perturbed_buf(:, 1) = tmpRef(:, 1)
        tmp_totwalkers = nPertRefs
    end subroutine create_perturbed_ref