find_switches_ilut Subroutine

    subroutine find_switches_ilut(ilut, ind, lower, upper)
        ! for single excitations this checks for available switches around an
        ! already chosen index
        integer(n_int), intent(in) :: ilut(0:GugaBits%len_tot)
        integer, intent(in) :: ind
        integer, intent(out) :: lower, upper

        integer :: i
        ! set defaults if no such switches are available
        lower = 1
        upper = nSpatOrbs

        ! i think i could improve that with the new trailz, leadz routines..

        if (isOne(ilut, ind)) then
            do i = ind - 1, 2, -1
                if (isTwo(ilut, i)) then
                    lower = i
                    exit
                end if
            end do
            do i = ind + 1, nSpatOrbs - 1
                if (isTwo(ilut, i)) then
                    upper = i
                    exit
                end if
            end do
        else if (isTwo(ilut, ind)) then
            do i = ind - 1, 2, -1
                if (isOne(ilut, i)) then
                    lower = i
                    exit
                end if
            end do
            do i = ind + 1, nSpatOrbs - 1
                if (isOne(ilut, i)) then
                    upper = i
                    exit
                end if
            end do
        end if

    end subroutine find_switches_ilut