checkInputGUGA Subroutine

    subroutine checkInputGUGA()
        ! routine to check if all the input parameters given are consistent
        ! and otherwise stops the excecution
        ! is called inf checkinput() in file readinput.F90
        character(*), parameter :: this_routine = 'checkInputGUGA'

        if (tSPN) then
            call stop_all(this_routine, &
                          "GUGA not yet implemented with spin restriction SPIN-RESTRICT!")
        end if

        if (tHPHF) then
            call stop_all(this_routine, &
                          "GUGA not compatible with HPHF option!")
        end if

        if (tSpinProject) then
            call stop_all(this_routine, &
                          "GUGA not compatible with tSpinProject!")
        end if

        ! with the new UEG/Hubbard implementation of the excitation generator
        ! i need symmetry actually!! or otherwise its wrong
        ! have to somehow find out how to check if k-point symmetry is
        ! provided
        if (tGen_sym_guga_ueg .and. lNoSymmetry .and. .not. treal) then
            call stop_all(this_routine, &
                          "UEG/Hubbard implementation of GUGA excitation generator needs symmetry but NOSYMMETRY set! abort!")
        end if

        ! in the real-space do not reorder the orbitals!
        if (treal) t_guga_noreorder = .true.

        if (tExactSizeSpace) then
            call stop_all(this_routine, &
                          "calculation of exact Hilbert space size not yet implemented with GUGA!")
        end if

        if (tUEGNewGenerator) then
            call stop_all(this_routine, &
                          "wrong input: ueg excitation generator chosen! abort!")
        end if

        if (tPickVirtUniform) then
            call stop_all(this_routine, &
                          "wrong input: tPickVirtUniform excitation generator chosen! abort!")
        end if

        if (tGenHelWeighted) then
            call stop_all(this_routine, &
                          "wrong input: tGenHelWeighted excitation generator chosen with GUGA! abort!")
        end if

        if (tGen_4ind_2) then
            call stop_all(this_routine, &
                          "wrong input: tGen_4ind_2 excitation generator chosen with GUGA! abort!")
        end if

        if (tGen_4ind_weighted) then
            call stop_all(this_routine, &
                          "wrong input: tGen_4ind_weighted excitation generator chosen with GUGA! abort!")
        end if

        if (tGen_4ind_reverse) then
            call stop_all(this_routine, &
                          "wrong input: tGen_4ind_reverse excitation generator chosen with GUGA! abort!")
        end if

        if (.not. tNoBrillouin) then
            call stop_all(this_routine, &
                          "Brillouin theorem not valid for GUGA approach!(I think atleast...)")
        end if

        ! also check if provided input values match:
        ! CONVENTION: STOT in units of h/2!
        if (STOT > nEl) then
            call stop_all(this_routine, &
                          "total spin S in units of h/2 cannot be higher than number of electrons!")
        end if

        if (mod(STOT, 2) /= mod(nEl, 2)) then
            call stop_all(this_routine, &
                          "number of electrons nEl and total spin S in units of h/2 must have same parity!")
        end if

        ! maybe more to come...
        ! UHF basis is also not compatible with guga? or not... or atleast
        ! i am not yet implementing it in such a way so it can work
        if (tUHF) then
            call stop_all(this_routine, &
                          "GUGA approach and UHF basis not yet (or never?) compatible!")
        end if

        if (tRealCoeffByExcitLevel) then
            if (RealCoeffExcitThresh > 2) then
                call stop_all(this_routine, &
                              "can only determine up to excit level 2 in GUGA for now!")
            end if
        end if

        if (tReplicaEstimates) then
            call stop_all(this_routine, &
                          "'replica-estimates' not yet implemented with GUGA")
        end if

        if (tPreCond) then
            call stop_all(this_routine, &
                          "'precond' not yet implemented with GUGA. mostly because of communication")
        end if

    end subroutine checkInputGUGA