calc_fullstart_fullstop_mixed_ex Subroutine

    pure subroutine calc_fullstart_fullstop_mixed_ex(ilutI, csf_i, ilutJ, csf_j, excitInfo, &
                                                mat_ele, t_hamil, rdm_ind, rdm_mat)
        integer(n_int), intent(in) :: ilutI(0:niftot), ilutJ(0:niftot)
        type(CSF_Info_t), intent(in) :: csf_i, csf_j
        type(ExcitationInformation_t), intent(in) :: excitInfo
        HElement_t(dp), intent(out) :: mat_ele
        logical, intent(in), optional :: t_hamil
        integer(int_rdm), intent(out), allocatable, optional :: rdm_ind(:)
        real(dp), intent(out), allocatable, optional :: rdm_mat(:)

        integer(n_int) :: tmp_I(0:nifguga), tmp_J(0:nifguga)
        logical :: t_hamil_
        integer :: delta_b(nSpatOrbs)

        def_default(t_hamil_, t_hamil, .true.)

        ! set default for early exits
        mat_ele = h_cast(0.0_dp)
        delta_b = csf_i%B_int - csf_j%B_int

        associate (ii => excitInfo%i, jj => excitInfo%j, kk => excitInfo%k, &
                   ll => excitInfo%l, start => excitInfo%fullstart, &
                   ende => excitInfo%fullEnd)

            if (any(abs(delta_b) > 2)) return

            call convert_ilut_toGUGA(ilutI, tmp_I)
            call convert_ilut_toGUGA(ilutJ, tmp_J)

            if (t_hamil_ .or. (tFillingStochRDMOnFly .and. present(rdm_mat))) then
                if (present(rdm_mat)) then
                    call calc_mixed_contr_integral(tmp_I, csf_i, tmp_J, start, ende, &
                                                    mat_ele, rdm_ind, rdm_mat)
                else
                    call calc_mixed_contr_integral(tmp_I, csf_i, tmp_J, start, ende, &
                                                mat_ele)
                end if
            end if
        end associate
    end subroutine calc_fullstart_fullstop_mixed_ex