OrderCoeffT1 Subroutine

    subroutine OrderCoeffT1()

        use RotateOrbsData, only: SymLabelList3_rot
        use LoggingData, only: tTruncRODump

        integer :: x, i, ierr, StartSort, EndSort, NoOcc
        character(len=*), parameter :: t_r = 'OrderCoeffT1'

        ! Here, if symmetry is kept, we are going to have to reorder the
        ! eigenvectors according to the size of the eigenvalues, while taking
        ! the orbital labels (and therefore symmetries) with them. This will be
        ! put back into MP2VDM from MP2VDMTemp.

        ! Want to reorder the eigenvalues from largest to smallest, taking the
        ! eigenvectors with them and the symmetry as well. If using spin
        ! orbitals, do this for the alpha spin and then the beta.

        OrderCoeff_Time%timer_name = 'OrderCoeff'
        call set_timer(OrderCoeff_Time, 30)

        if (tTruncRODump) then
            ! If we are truncating, the orbitals stay in this order, so we want
            ! to take their symmetries with them.
            allocate(SymOrbs_rotTemp(NoOrbs), stat=ierr)
            call LogMemAlloc('SymOrbs_rotTemp', NoOrbs, 4, t_r, SymOrbs_rotTempTag, ierr)
            SymOrbs_rotTemp(:) = 0

            if (tStoreSpinOrbs) then
                do i = 1, NoOrbs
                    SymOrbs_rotTemp(i) = int(G1(SymLabelList2_rot(i))%sym%S, 4)
                end do
            else
                do i = 1, NoOrbs
                    SymOrbs_rotTemp(i) = int(G1(SymLabelList2_rot(i) * 2)%sym%S, 4)
                end do
            end if

            do x = 1, NoSpinCyc

                if (x == 1) then
                    if (tSeparateOccVirt) then
                        if (tStoreSpinOrbs) then
                            NoOcc = nOccBeta
                        else
                            NoOcc = NEl / 2
                        end if
                    else
                        NoOcc = 0
                    end if
                    StartSort = 1
                    EndSort = SpatOrbs
                    if (tRotateVirtOnly) StartSort = NoOcc + 1
                    if (tRotateOccOnly) EndSort = NoOcc
                else if (x == 2) then
                    if (tSeparateOccVirt) then
                        NoOcc = nOccAlpha
                    else
                        NoOcc = 0
                    end if
                    StartSort = SpatOrbs + 1
                    EndSort = NoOrbs
                    if (tRotateVirtOnly) StartSort = SpatOrbs + NoOcc + 1
                    if (tRotateOccOnly) EndSort = NoOcc + SpatOrbs
                end if

                call sort(Evalues(startSort:endSort), natOrbMat(startSort:endSort, startSort:endSort), &
                          SymOrbs_rotTemp(startSort:endSort))

            end do

        else

            ! If we are not truncating, the orbitals get put back into their
            ! original order, so the symmetry information is still correct,
            ! no need for the SymOrbs_rot array. Instead, just take the labels
            ! of SymLabelList3_rot with them.
            do x = 1, NoSpinCyc

                if (x == 1) then
                    if (tSeparateOccVirt) then
                        if (tStoreSpinOrbs) then
                            NoOcc = nOccBeta
                        else
                            NoOcc = NEl / 2
                        end if
                    else
                        NoOcc = 0
                    end if
                    StartSort = 1
                    EndSort = SpatOrbs
                    if (tRotateOccOnly) EndSort = NoOcc
                    if (tRotateVirtOnly) StartSort = NoOcc + 1

                else if (x == 2) then
                    if (tSeparateOccVirt) then
                        NoOcc = nOccAlpha
                    else
                        NoOcc = 0
                    end if
                    StartSort = SpatOrbs + 1
                    EndSort = NoOrbs
                    if (tRotateOccOnly) EndSort = SpatOrbs + NoOcc
                    if (tRotateVirtOnly) StartSort = SpatOrbs + NoOcc + 1
                end if

                call sort(EValues(startSort:endSort), NatOrbMat(startSort:endSort, startSort:endSort), &
                          SymLabelList3_rot(startSort:endSort))
            end do

        end if

        call halt_timer(OrderCoeff_Time)

        write(stdout, *) 'Eigen-values: '
        do i = 1, NoOrbs
            write(stdout, *) Evalues(i)
        end do

    end subroutine OrderCoeffT1