quack/src/QuAcK/QuAcK.f90

program QuAcK

  implicit none
  include 'parameters.h'

  logical                       :: doSph
  logical                       :: unrestricted = .false.
  logical                       :: doRHF,doUHF,doMOM 
  logical                       :: dostab
  logical                       :: doKS
  logical                       :: doMP2,doMP3
  logical                       :: doCCD,dopCCD,doDCD,doCCSD,doCCSDT
  logical                       :: do_drCCD,do_rCCD,do_crCCD,do_lCCD
  logical                       :: doCIS,doCIS_D,doCID,doCISD,doFCI
  logical                       :: doRPA,doRPAx,docrRPA,doppRPA
  logical                       :: doADC
  logical                       :: doG0F2,doevGF2,doqsGF2,doG0F3,doevGF3
  logical                       :: doG0W0,doevGW,doqsGW,doufG0W0,doufGW,doSRGqsGW
  logical                       :: doG0T0pp,doevGTpp,doqsGTpp
  logical                       :: doG0T0eh,doevGTeh,doqsGTeh

  integer                       :: nNuc,nBas,nBasCABS
  integer                       :: nEl(nspin)
  integer                       :: nC(nspin)
  integer                       :: nO(nspin)
  integer                       :: nV(nspin)
  integer                       :: nR(nspin)
  integer                       :: nS(nspin)
  double precision              :: ENuc,ERHF,EUHF,Norm
  double precision              :: EcMP2(3),EcMP3

  double precision,allocatable  :: ZNuc(:),rNuc(:,:)
  double precision,allocatable  :: cHF(:,:,:),eHF(:,:),PHF(:,:,:)
  double precision,allocatable  :: Vxc(:,:)

  double precision,allocatable  :: eG0W0(:,:)
  double precision,allocatable  :: eG0T0(:,:)

  logical                       :: doACFDT
  logical                       :: exchange_kernel
  logical                       :: doXBS

  double precision,allocatable  :: S(:,:)
  double precision,allocatable  :: T(:,:)
  double precision,allocatable  :: V(:,:)
  double precision,allocatable  :: Hc(:,:)
  double precision,allocatable  :: X(:,:)
  double precision,allocatable  :: dipole_int_AO(:,:,:)
  double precision,allocatable  :: dipole_int_MO(:,:,:)
  double precision,allocatable  :: dipole_int_aa(:,:,:)
  double precision,allocatable  :: dipole_int_bb(:,:,:)
  double precision,allocatable  :: F_AO(:,:)
  double precision,allocatable  :: F_MO(:,:)
  double precision,allocatable  :: ERI_AO(:,:,:,:)
  double precision,allocatable  :: ERI_MO(:,:,:,:)
  integer                       :: ixyz
  integer                       :: bra1,bra2
  integer                       :: ket1,ket2
  double precision,allocatable  :: ERI_MO_aaaa(:,:,:,:)
  double precision,allocatable  :: ERI_MO_aabb(:,:,:,:)
  double precision,allocatable  :: ERI_MO_bbbb(:,:,:,:)
  double precision,allocatable  :: ERI_ERF_AO(:,:,:,:)
  double precision,allocatable  :: ERI_ERF_MO(:,:,:,:)

  double precision              :: start_QuAcK  ,end_QuAcK    ,t_QuAcK
  double precision              :: start_int    ,end_int      ,t_int  
  double precision              :: start_HF     ,end_HF       ,t_HF
  double precision              :: start_stab   ,end_stab     ,t_stab
  double precision              :: start_KS     ,end_KS       ,t_KS
  double precision              :: start_AOtoMO ,end_AOtoMO   ,t_AOtoMO
  double precision              :: start_CC     ,end_CC       ,t_CC 
  double precision              :: start_CI     ,end_CI       ,t_CI 
  double precision              :: start_RPA    ,end_RPA      ,t_RPA 
  double precision              :: start_GF     ,end_GF       ,t_GF 
  double precision              :: start_GW     ,end_GW       ,t_GW 
  double precision              :: start_GT     ,end_GT       ,t_GT
  double precision              :: start_MP     ,end_MP       ,t_MP 

  integer                       :: maxSCF_HF,n_diis_HF
  double precision              :: thresh_HF,level_shift
  logical                       :: DIIS_HF,guess_type,ortho_type,mix

  logical                       :: regMP

  integer                       :: maxSCF_CC,n_diis_CC
  double precision              :: thresh_CC
  logical                       :: DIIS_CC

  logical                       :: singlet
  logical                       :: triplet
  logical                       :: spin_conserved
  logical                       :: spin_flip
  logical                       :: TDA

  integer                       :: maxSCF_GF,n_diis_GF,renormGF
  double precision              :: thresh_GF
  logical                       :: DIIS_GF,linGF,regGF
  double precision              :: eta_GF

  integer                       :: maxSCF_GW,n_diis_GW
  double precision              :: thresh_GW
  logical                       :: DIIS_GW,COHSEX,TDA_W,linGW,regGW
  double precision              :: eta_GW

  integer                       :: maxSCF_GT,n_diis_GT
  double precision              :: thresh_GT
  logical                       :: DIIS_GT,TDA_T,linGT,regGT
  double precision              :: eta_GT

  logical                       :: BSE,dBSE,dTDA,evDyn,ppBSE,BSE2

! Hello World

  write(*,*)
  write(*,*) '******************************************************************************************'
  write(*,*) '*            QuAcK                       QuAcK                         QuAcK             *'
  write(*,*) '*   __        __        __       __        __        __       __        __        __     *'
  write(*,*) '* <(o )___  <(o )___  <(o )___ <(o )___  <(o )___  <(o )___ <(o )___  <(o )___  <(o )___ *'
  write(*,*) '* ( ._> /   ( ._> /   ( ._> /  ( ._> /   ( ._> /   ( ._> /  ( ._> /   ( ._> /   ( ._> /  *'
  write(*,*) '*|--------------------------------------------------------------------------------------|*'
  write(*,*) '******************************************************************************************'
  write(*,*)

! Spherium calculation?
  
  doSph = .false.

  call wall_time(start_QuAcK)

! Which calculations do you want to do?

  call read_methods(doRHF,doUHF,doKS,doMOM,            &
                    doMP2,doMP3,                       &
                    doCCD,dopCCD,doDCD,doCCSD,doCCSDT, &
                    do_drCCD,do_rCCD,do_crCCD,do_lCCD, &
                    doCIS,doCIS_D,doCID,doCISD,doFCI,  & 
                    doRPA,doRPAx,docrRPA,doppRPA,      &
                    doG0F2,doevGF2,doqsGF2,            & 
                    doG0F3,doevGF3,                    &
                    doG0W0,doevGW,doqsGW,doSRGqsGW,    &
                    doufG0W0,doufGW,                   &
                    doG0T0pp,doevGTpp,doqsGTpp,        &
                    doG0T0eh,doevGTeh,doqsGTeh)

! Read options for methods

  call read_options(maxSCF_HF,thresh_HF,DIIS_HF,n_diis_HF,guess_type,ortho_type,mix,level_shift,dostab, &
                    regMP,                                                                              &
                    maxSCF_CC,thresh_CC,DIIS_CC,n_diis_CC,                                              &
                    TDA,singlet,triplet,spin_conserved,spin_flip,                                       &
                    maxSCF_GF,thresh_GF,DIIS_GF,n_diis_GF,linGF,eta_GF,renormGF,regGF,                  &
                    maxSCF_GW,thresh_GW,DIIS_GW,n_diis_GW,linGW,eta_GW,regGW,COHSEX,TDA_W,              &  
                    maxSCF_GT,thresh_GT,DIIS_GT,n_diis_GT,linGT,eta_GT,regGT,TDA_T,                     & 
                    doACFDT,exchange_kernel,doXBS,                                                      &
                    BSE,dBSE,dTDA,evDyn,ppBSE,BSE2)

!------------------------------------------------------------------------
! Read input information
!------------------------------------------------------------------------

! Read number of atoms, number of electrons of the system
! nC   = number of core orbitals
! nO   = number of occupied orbitals
! nV   = number of virtual orbitals (see below)
! nR   = number of Rydberg orbitals 
! nBas = number of basis functions (see below)
!      = nO + nV
! nS   = number of single excitation 
!      = nO*nV

  call read_molecule(nNuc,nEl(:),nO(:),nC(:),nR(:))
  allocate(ZNuc(nNuc),rNuc(nNuc,ncart))

! Read geometry

  call read_geometry(nNuc,ZNuc,rNuc,ENuc)

! allocate(CenterShell(maxShell,ncart),TotAngMomShell(maxShell),KShell(maxShell),DShell(maxShell,maxK), & 
!          ExpShell(maxShell,maxK),max_ang_mom(nNuc),min_exponent(nNuc,maxL+1),max_exponent(nNuc))

!------------------------------------------------------------------------
! Read basis set information from PySCF
!------------------------------------------------------------------------

  call read_basis_pyscf (nBas,nO,nV)
! call read_basis(nNuc,rNuc,nBas,nO,nV,nShell,TotAngMomShell,CenterShell,KShell,DShell,ExpShell, & 
!                 max_ang_mom,min_exponent,max_exponent)
  nS(:) = (nO(:) - nC(:))*(nV(:) - nR(:))

!------------------------------------------------------------------------
! Read one- and two-electron integrals
!------------------------------------------------------------------------

! Memory allocation for one- and two-electron integrals

  allocate(cHF(nBas,nBas,nspin),eHF(nBas,nspin),eG0W0(nBas,nspin),eG0T0(nBas,nspin),PHF(nBas,nBas,nspin), &
           S(nBas,nBas),T(nBas,nBas),V(nBas,nBas),Hc(nBas,nBas),X(nBas,nBas),ERI_AO(nBas,nBas,nBas,nBas), &
           dipole_int_AO(nBas,nBas,ncart),dipole_int_MO(nBas,nBas,ncart),Vxc(nBas,nspin),F_AO(nBas,nBas))

! Read integrals

  call wall_time(start_int)

  if(doSph) then

    call read_integrals_sph(nBas,S,T,V,Hc,ERI_AO)  

  else

    call read_integrals(nBas,S,T,V,Hc,ERI_AO)
    call read_dipole_integrals(nBas,dipole_int_AO)

  end if

  call wall_time(end_int)

    t_int = end_int - start_int
    write(*,*)
    write(*,'(A65,1X,F9.3,A8)') 'Total wall time for reading integrals = ',t_int,' seconds'
    write(*,*)

! Compute orthogonalization matrix

  call orthogonalization_matrix(ortho_type,nBas,S,X)

!------------------------------------------------------------------------
! Compute RHF energy
!------------------------------------------------------------------------

  if(doRHF) then

   ! Check that RHF calculation is worth doing...

   if(nO(1) /= nO(2)) then
     write(*,*) ' !!! The system does not appear to be closed shell !!!'
     write(*,*) 
     stop
   end if

    call wall_time(start_HF)
    call RHF(maxSCF_HF,thresh_HF,n_diis_HF,guess_type,level_shift,nNuc,ZNuc,rNuc,ENuc, &
             nBas,nO,S,T,V,Hc,F_AO,ERI_AO,dipole_int_AO,X,ERHF,eHF,cHF,PHF,Vxc)
    call wall_time(end_HF)

    t_HF = end_HF - start_HF
    write(*,'(A65,1X,F9.3,A8)') 'Total wall time for RHF = ',t_HF,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute UHF energy
!------------------------------------------------------------------------

  if(doUHF) then

    ! Switch on the unrestricted flag
    unrestricted = .true.

    call cpu_time(start_HF)
    call UHF(maxSCF_HF,thresh_HF,n_diis_HF,guess_type,mix,level_shift,nNuc,ZNuc,rNuc,ENuc, & 
             nBas,nO,S,T,V,Hc,ERI_AO,dipole_int_AO,X,EUHF,eHF,cHF,PHF,Vxc)
    call cpu_time(end_HF)

    t_HF = end_HF - start_HF
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for UHF = ',t_HF,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute KS energy
!------------------------------------------------------------------------

  if(doKS) then

    ! Switch on the unrestricted flag
    unrestricted = .true.

    call cpu_time(start_KS)
!   call eDFT(maxSCF_HF,thresh_HF,n_diis_HF,guess_type,mix,level_shift,nNuc,ZNuc,rNuc,ENuc,nBas,nEl,nC, & 
!             nO,nV,nR,nShell,TotAngMomShell,CenterShell,KShell,DShell,ExpShell,            &
!             max_ang_mom,min_exponent,max_exponent,S,T,V,Hc,X,ERI_AO,dipole_int_AO,EUHF,eHF,cHF,PHF,Vxc)
             
    call cpu_time(end_KS)

    t_KS = end_KS - start_KS
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for KS = ',t_KS,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Maximum overlap method
!------------------------------------------------------------------------

  if(doMOM) then

    call cpu_time(start_HF)

    if(unrestricted) then

!     call UMOM()

    else

      call MOM(maxSCF_HF,thresh_HF,n_diis_HF,guess_type,nNuc,ZNuc,rNuc,ENuc, &
             nBas,nO,S,T,V,Hc,ERI_AO,dipole_int_AO,X,ERHF,eHF,cHF,PHF,Vxc)

    end if

    call cpu_time(end_HF)

    t_HF = end_HF - start_HF
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for MOM = ',t_HF,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! AO to MO integral transform for post-HF methods
!------------------------------------------------------------------------

  call wall_time(start_AOtoMO)

  write(*,*)
  write(*,*) 'AO to MO transformation... Please be patient'
  write(*,*)

  if(doSph) then

    allocate(ERI_MO(nBas,nBas,nBas,nBas))
    ERI_MO(:,:,:,:) = ERI_AO(:,:,:,:)
    print*,'!!! MO = AO !!!'
    deallocate(ERI_AO)

  else

    if(unrestricted) then

      ! Read and transform dipole-related integrals
    
      allocate(dipole_int_aa(nBas,nBas,ncart),dipole_int_bb(nBas,nBas,ncart))
      dipole_int_aa(:,:,:) = dipole_int_AO(:,:,:)
      dipole_int_bb(:,:,:) = dipole_int_AO(:,:,:)
      do ixyz=1,ncart
          call AOtoMO_transform(nBas,cHF(:,:,1),dipole_int_aa(:,:,ixyz))
          call AOtoMO_transform(nBas,cHF(:,:,2),dipole_int_bb(:,:,ixyz))
      end do 

      ! Memory allocation
     
      allocate(ERI_MO_aaaa(nBas,nBas,nBas,nBas),ERI_MO_aabb(nBas,nBas,nBas,nBas),ERI_MO_bbbb(nBas,nBas,nBas,nBas))
     
      ! 4-index transform for (aa|aa) block
     
      bra1 = 1
      bra2 = 1
      ket1 = 1
      ket2 = 1
      call AOtoMO_integral_transform(bra1,bra2,ket1,ket2,nBas,cHF,ERI_AO,ERI_MO_aaaa)
      
      ! 4-index transform for (aa|bb) block
     
      bra1 = 1
      bra2 = 1
      ket1 = 2
      ket2 = 2
      call AOtoMO_integral_transform(bra1,bra2,ket1,ket2,nBas,cHF,ERI_AO,ERI_MO_aabb)
     
      ! 4-index transform for (bb|bb) block
     
      bra1 = 2
      bra2 = 2
      ket1 = 2
      ket2 = 2
      call AOtoMO_integral_transform(bra1,bra2,ket1,ket2,nBas,cHF,ERI_AO,ERI_MO_bbbb)

    else

      ! Memory allocation
     
      allocate(ERI_MO(nBas,nBas,nBas,nBas))
      allocate(F_MO(nBas,nBas))
 
      ! Read and transform dipole-related integrals
    
      dipole_int_MO(:,:,:) = dipole_int_AO(:,:,:)
      do ixyz=1,ncart
        call AOtoMO_transform(nBas,cHF,dipole_int_MO(:,:,ixyz))
      end do 

      ! 4-index transform 
     
      bra1 = 1
      bra2 = 1
      ket1 = 1
      ket2 = 1
      call AOtoMO_integral_transform(bra1,bra2,ket1,ket2,nBas,cHF,ERI_AO,ERI_MO)

      F_MO(:,:) = F_AO(:,:)
      call AOtoMO_transform(nBas,cHF,F_MO)

    end if

  end if

  call wall_time(end_AOtoMO)

  t_AOtoMO = end_AOtoMO - start_AOtoMO
  write(*,'(A65,1X,F9.3,A8)') 'Total wall time for AO to MO transformation = ',t_AOtoMO,' seconds'
  write(*,*)

!------------------------------------------------------------------------
! Stability analysis of HF solution
!------------------------------------------------------------------------

  if(dostab) then

    call cpu_time(start_stab)

    if(unrestricted) then

      call UHF_stability(nBas,nC,nO,nV,nR,nS,eHF,ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb)

    else

      call RHF_stability(nBas,nC,nO,nV,nR,nS,eHF,ERI_MO)

    end if

    call cpu_time(end_stab)

    t_stab = end_stab - start_stab
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for stability analysis = ',t_stab,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute MP2 energy
!------------------------------------------------------------------------

  if(doMP2) then

    call cpu_time(start_MP)

    if(unrestricted) then

      call UMP2(nBas,nC,nO,nV,nR,ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb,ENuc,EUHF,eHF,EcMP2)

    else

      call MP2(regMP,nBas,nC,nO,nV,nR,ERI_MO,ENuc,ERHF,eHF,EcMP2)

    end if

    call cpu_time(end_MP)

    t_MP = end_MP - start_MP
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for MP2 = ',t_MP,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute MP3 energy
!------------------------------------------------------------------------

  if(doMP3) then

    call cpu_time(start_MP)
    
    if(unrestricted) then

      write(*,*) 'MP3 NYI for UHF reference'
      stop

    else

      call MP3(nBas,nC,nO,nV,nR,ERI_MO,eHF,ENuc,ERHF)

    end if

    call cpu_time(end_MP)

    t_MP = end_MP - start_MP
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for MP3 = ',t_MP,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform CCD calculation
!------------------------------------------------------------------------

  if(doCCD) then

    call cpu_time(start_CC)
    call CCD(.false.,maxSCF_CC,thresh_CC,n_diis_CC,nBas,nC,nO,nV,nR,ERI_MO,ENuc,ERHF,eHF)
    call cpu_time(end_CC)

    t_CC = end_CC - start_CC
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for CCD = ',t_CC,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform DCD calculation
!------------------------------------------------------------------------

  if(doDCD) then

    call cpu_time(start_CC)
    call DCD(maxSCF_CC,thresh_CC,n_diis_CC,nBas,nC,nO,nV,nR, & 
             ERI_MO,ENuc,ERHF,eHF)
    call cpu_time(end_CC)

    t_CC = end_CC - start_CC
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for DCD = ',t_CC,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform CCSD or CCSD(T) calculation
!------------------------------------------------------------------------

  if(doCCSDT) doCCSD = .true.

  if(doCCSD) then

    call cpu_time(start_CC)
    call CCSD(.false.,maxSCF_CC,thresh_CC,n_diis_CC,doCCSDT,nBas,nC,nO,nV,nR,ERI_MO,ENuc,ERHF,eHF)
    call cpu_time(end_CC)

    t_CC = end_CC - start_CC
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for CCSD or CCSD(T)= ',t_CC,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform direct ring CCD calculation
!------------------------------------------------------------------------

  if(do_drCCD) then

    call cpu_time(start_CC)
    call drCCD(maxSCF_CC,thresh_CC,n_diis_CC,nBas,nC,nO,nV,nR,ERI_MO,ENuc,ERHF,eHF)
    call cpu_time(end_CC)

    t_CC = end_CC - start_CC
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for direct ring CCD = ',t_CC,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform ring CCD calculation
!------------------------------------------------------------------------

  if(do_rCCD) then

    call cpu_time(start_CC)
    call rCCD(.false.,maxSCF_CC,thresh_CC,n_diis_CC,nBas,nC,nO,nV,nR,ERI_MO,ENuc,ERHF,eHF,eHF)
    call cpu_time(end_CC)

    t_CC = end_CC - start_CC
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for rCCD = ',t_CC,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform crossed-ring CCD calculation
!------------------------------------------------------------------------

  if(do_crCCD) then

    call cpu_time(start_CC)
    call crCCD(maxSCF_CC,thresh_CC,n_diis_CC,nBas,nC,nO,nV,nR,ERI_MO,ENuc,ERHF,eHF)
    call cpu_time(end_CC)

    t_CC = end_CC - start_CC
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for crossed-ring CCD = ',t_CC,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform ladder CCD calculation
!------------------------------------------------------------------------

  if(do_lCCD) then

    call cpu_time(start_CC)
    call lCCD(maxSCF_CC,thresh_CC,n_diis_CC,nBas,nC,nO,nV,nR, &
              ERI_MO,ENuc,ERHF,eHF)
    call cpu_time(end_CC)

    t_CC = end_CC - start_CC
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for ladder CCD = ',t_CC,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform pair CCD calculation
!------------------------------------------------------------------------

  if(dopCCD) then

    call cpu_time(start_CC)
    call pCCD(maxSCF_CC,thresh_CC,n_diis_CC,nBas,nC,nO,nV,nR,ERI_MO,ENuc,ERHF,eHF)
    call cpu_time(end_CC)

    t_CC = end_CC - start_CC
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for pair CCD = ',t_CC,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute CIS excitations
!------------------------------------------------------------------------

  if(doCIS) then

    call cpu_time(start_CI)

    if(unrestricted) then

      call UCIS(spin_conserved,spin_flip,nBas,nC,nO,nV,nR,nS,ERI_MO_aaaa,ERI_MO_aabb, & 
                ERI_MO_bbbb,dipole_int_aa,dipole_int_bb,eHF,cHF,S)

   else 

      call CIS(singlet,triplet,doCIS_D,nBas,nC,nO,nV,nR,nS,ERI_MO,dipole_int_MO,eHF)

    end if

    call cpu_time(end_CI)

    t_CI = end_CI - start_CI
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for CIS = ',t_CI,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute CID excitations
!------------------------------------------------------------------------

  if(doCID) then

    call cpu_time(start_CI)
    call CID(singlet,triplet,nBas,nC,nO,nV,nR,ERI_MO,F_MO,ERHF)
    call cpu_time(end_CI)

    t_CI = end_CI - start_CI
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for CID = ',t_CI,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute CISD excitations
!------------------------------------------------------------------------

  if(doCISD) then

    call cpu_time(start_CI)
    call CISD(singlet,triplet,nBas,nC,nO,nV,nR,ERI_MO,F_MO,ERHF)
    call cpu_time(end_CI)

    t_CI = end_CI - start_CI
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for CISD = ',t_CI,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute (direct) RPA excitations
!------------------------------------------------------------------------

  if(doRPA) then

    call cpu_time(start_RPA)
    if(unrestricted) then

       call URPA(TDA,doACFDT,exchange_kernel,spin_conserved,spin_flip,0d0,nBas,nC,nO,nV,nR,nS,ENuc,EUHF, &
                  ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb,dipole_int_aa,dipole_int_bb,eHF,cHF,S)

    else

      call RPA(TDA,doACFDT,exchange_kernel,singlet,triplet,0d0,nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_MO,dipole_int_MO,eHF)

    end if
    call cpu_time(end_RPA)

    t_RPA = end_RPA - start_RPA
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for RPA = ',t_RPA,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute RPAx (RPA with exchange) excitations
!------------------------------------------------------------------------

  if(doRPAx) then

    call cpu_time(start_RPA)
    if(unrestricted) then

       call URPAx(TDA,doACFDT,exchange_kernel,spin_conserved,spin_flip,0d0,nBas,nC,nO,nV,nR,nS,ENuc,EUHF, &
                  ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb,dipole_int_aa,dipole_int_bb,eHF,cHF,S)

    else 

     call RPAx(TDA,doACFDT,exchange_kernel,singlet,triplet,0d0,nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_MO,dipole_int_MO,eHF)

    end if
    call cpu_time(end_RPA)

    t_RPA = end_RPA - start_RPA
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for RPAx = ',t_RPA,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute cr-RPA excitations
!------------------------------------------------------------------------

  if(docrRPA) then

    call cpu_time(start_RPA)
    call crRPA(TDA,doACFDT,exchange_kernel,singlet,triplet,0d0,nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_MO,dipole_int_MO,eHF)
    call cpu_time(end_RPA)

    t_RPA = end_RPA - start_RPA
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for pp-RPA = ',t_RPA,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute pp-RPA excitations
!------------------------------------------------------------------------

  if(doppRPA) then

    call cpu_time(start_RPA)

    if(unrestricted) then 

      call ppURPA(TDA,doACFDT,spin_conserved,spin_flip,nBas,nC,nO,nV,nR,ENuc,EUHF,ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb,eHF)

    else

      call ppRPA(TDA,doACFDT,singlet,triplet,nBas,nC,nO,nV,nR,ENuc,ERHF,ERI_MO,dipole_int_MO,eHF)

    end if

    call cpu_time(end_RPA)

    t_RPA = end_RPA - start_RPA
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for pp-RPA = ',t_RPA,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute ADC excitations
!------------------------------------------------------------------------

! if(doADC) then

!   call cpu_time(start_ADC)
!   call ADC(singlet,triplet,maxSCF_GF,thresh_GF,n_diis_GF, & 
!            nBas,nC,nO,nV,nR,eHF,ERI_MO)
!   call cpu_time(end_ADC)

!   t_ADC = end_ADC - start_ADC
!   write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for ADC = ',t_ADC,' seconds'
!   write(*,*)

! end if

!------------------------------------------------------------------------
! Compute G0F2 electronic binding energies
!------------------------------------------------------------------------

  if(doG0F2) then

    call cpu_time(start_GF)

    if(unrestricted) then

      call UG0F2(BSE,TDA,dBSE,dTDA,evDyn,spin_conserved,spin_flip,linGF,eta_GF,regGF,        &
                 nBas,nC,nO,nV,nR,nS,ENuc,EUHF,S,ERI_AO,ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb, & 
                 dipole_int_aa,dipole_int_bb,eHF)

    else

      call G0F2(BSE,TDA,dBSE,dTDA,evDyn,singlet,triplet,linGF,eta_GF,regGF, & 
                nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_MO,dipole_int_MO,eHF)

    end if

    call cpu_time(end_GF)

    t_GF = end_GF - start_GF
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for GF2 = ',t_GF,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute evGF2 electronic binding energies
!------------------------------------------------------------------------

  if(doevGF2) then

    call cpu_time(start_GF)

    if(unrestricted) then

      call evUGF2(maxSCF_GF,thresh_GF,n_diis_GF,BSE,TDA,dBSE,dTDA,evDyn,spin_conserved,spin_flip,    &
                  eta_GF,regGF,nBas,nC,nO,nV,nR,nS,ENuc,EUHF,S,ERI_AO,ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb, & 
                  dipole_int_aa,dipole_int_bb,cHF,eHF)

    else

      call evGF2(BSE,TDA,dBSE,dTDA,evDyn,maxSCF_GF,thresh_GF,n_diis_GF, & 
                 singlet,triplet,linGF,eta_GF,regGF,nBas,nC,nO,nV,nR,nS,ENuc,ERHF, & 
                 ERI_MO,dipole_int_MO,eHF)

    end if

    call cpu_time(end_GF)

    t_GF = end_GF - start_GF
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for GF2 = ',t_GF,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform qsGF2 calculation
!------------------------------------------------------------------------

  if(doqsGF2) then 

    call cpu_time(start_GF)

    if(unrestricted) then

      call qsUGF2(maxSCF_GF,thresh_GF,n_diis_GF,BSE,TDA,dBSE,dTDA,evDyn,spin_conserved,spin_flip,eta_GF,regGF, &
                  nNuc,ZNuc,rNuc,ENuc,nBas,nC,nO,nV,nR,nS,EUHF,S,X,T,V,Hc,ERI_AO,                        & 
                  ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb,dipole_int_AO,dipole_int_aa,dipole_int_bb,PHF,cHF,eHF)

    else

      call qsGF2(maxSCF_GF,thresh_GF,n_diis_GF,BSE,TDA,dBSE,dTDA,evDyn,singlet,triplet,eta_GF,regGF,nNuc,ZNuc,rNuc,ENuc, & 
                 nBas,nC,nO,nV,nR,nS,ERHF,S,X,T,V,Hc,ERI_AO,ERI_MO,dipole_int_AO,dipole_int_MO,PHF,cHF,eHF)

    end if

    call cpu_time(end_GF)

    t_GF = end_GF - start_GF
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for qsGF2 = ',t_GF,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute G0F3 electronic binding energies
!------------------------------------------------------------------------

  if(doG0F3) then

    call cpu_time(start_GF)

    if(unrestricted) then

      print*,'!!! G0F3 NYI at the unrestricted level !!!'

    else

      call G0F3(renormGF,nBas,nC,nO,nV,nR,ERI_MO,eHF)

    end if

    call cpu_time(end_GF)

    t_GF = end_GF - start_GF
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for GF3 = ',t_GF,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute evGF3 electronic binding energies
!------------------------------------------------------------------------

  if(doevGF3) then

    call cpu_time(start_GF)

    if(unrestricted) then

      print*,'!!! evGF3 NYI at the unrestricted level !!!'

    else

      call evGF3(maxSCF_GF,thresh_GF,n_diis_GF,renormGF,nBas,nC,nO,nV,nR,ERI_MO,eHF)

    end if

    call cpu_time(end_GF)

    t_GF = end_GF - start_GF
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for GF3 = ',t_GF,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform G0W0 calculatiom
!------------------------------------------------------------------------

  eG0W0(:,:) = eHF(:,:)

  if(doG0W0) then
    
    call cpu_time(start_GW)
    if(unrestricted) then 

      call UG0W0(doACFDT,exchange_kernel,doXBS,COHSEX,BSE,TDA_W,TDA,dBSE,dTDA,evDyn,spin_conserved,spin_flip,   & 
                 linGW,eta_GW,regGW,nBas,nC,nO,nV,nR,nS,ENuc,EUHF,S,ERI_AO,ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb, & 
                 dipole_int_aa,dipole_int_bb,PHF,cHF,eHF,Vxc,eG0W0)
    else

      call G0W0(doACFDT,exchange_kernel,doXBS,COHSEX,BSE,BSE2,TDA_W,TDA,dBSE,dTDA,evDyn,ppBSE,singlet,triplet, &
                linGW,eta_GW,regGW,nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_AO,ERI_MO,dipole_int_MO,PHF,cHF,eHF,Vxc,eG0W0)
    end if

    call cpu_time(end_GW)
  
    t_GW = end_GW - start_GW
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for G0W0 = ',t_GW,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform evGW calculation
!------------------------------------------------------------------------

  if(doevGW) then

    call cpu_time(start_GW)
    if(unrestricted) then 

      call evUGW(maxSCF_GW,thresh_GW,n_diis_GW,doACFDT,exchange_kernel,doXBS,COHSEX,BSE,TDA_W,TDA,   &
                dBSE,dTDA,evDyn,spin_conserved,spin_flip,eta_GW,regGW,nBas,nC,nO,nV,nR,nS,ENuc,    &
                EUHF,S,ERI_AO,ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb,dipole_int_aa,dipole_int_bb, & 
                PHF,cHF,eHF,Vxc,eG0W0)

    else

      call evGW(maxSCF_GW,thresh_GW,n_diis_GW,doACFDT,exchange_kernel,doXBS,COHSEX,       &
                BSE,BSE2,TDA_W,TDA,dBSE,dTDA,evDyn,ppBSE,singlet,triplet,linGW,eta_GW,regGW, &
                nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_AO,ERI_MO,dipole_int_MO,PHF,cHF,eHF,Vxc,eG0W0)
    end if
    call cpu_time(end_GW)

    t_GW = end_GW - start_GW
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for evGW = ',t_GW,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform qsGW calculation
!------------------------------------------------------------------------

  if(doqsGW) then 

    call wall_time(start_GW)

    if(unrestricted) then 
    
      call qsUGW(maxSCF_GW,thresh_GW,n_diis_GW,doACFDT,exchange_kernel,doXBS,COHSEX,BSE,TDA_W,TDA, &
                 dBSE,dTDA,evDyn,spin_conserved,spin_flip,eta_GW,regGW,nNuc,ZNuc,rNuc,ENuc,nBas,nC,nO, &
                 nV,nR,nS,EUHF,S,X,T,V,Hc,ERI_AO,ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb,dipole_int_AO,      &
                 dipole_int_aa,dipole_int_bb,PHF,cHF,eHF)

    else
 
      call qsGW(maxSCF_GW,thresh_GW,n_diis_GW,doACFDT,exchange_kernel,doXBS,COHSEX,               &
                BSE,BSE2,TDA_W,TDA,dBSE,dTDA,evDyn,singlet,triplet,eta_GW,regGW,nNuc,ZNuc,rNuc,ENuc, & 
                nBas,nC,nO,nV,nR,nS,ERHF,S,X,T,V,Hc,ERI_AO,ERI_MO,dipole_int_AO,dipole_int_MO,PHF,cHF,eHF)

    end if

    call wall_time(end_GW)

    t_GW = end_GW - start_GW
    write(*,'(A65,1X,F9.3,A8)') 'Total wall time for qsGW = ',t_GW,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform SRG-qsGW calculation
!------------------------------------------------------------------------

  if(doSRGqsGW) then 

    call wall_time(start_GW)

    if(unrestricted) then 

    print*,'Unrestricted version of SRG-qsGW NYI'

    else
 
      call SRG_qsGW(maxSCF_GW,thresh_GW,n_diis_GW,doACFDT,exchange_kernel,doXBS,BSE,BSE2,TDA_W,TDA,dBSE,dTDA,evDyn, & 
                    singlet,triplet,eta_GW,nNuc,ZNuc,rNuc,ENuc,nBas,nC,nO,nV,nR,nS,ERHF,S,X,T,V,Hc,ERI_AO,ERI_MO,   & 
                    dipole_int_AO,dipole_int_MO,PHF,cHF,eHF)

    end if

    call wall_time(end_GW)

    t_GW = end_GW - start_GW
    write(*,'(A65,1X,F9.3,A8)') 'Total wall time for qsGW = ',t_GW,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform ufG0W0 calculatiom
!------------------------------------------------------------------------

  if(doufG0W0) then
    
    call cpu_time(start_GW)
    call ufG0W0(nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_MO,eHF,TDA_W)
    call cpu_time(end_GW)
  
    t_GW = end_GW - start_GW
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for ufG0W0 = ',t_GW,' seconds'
    write(*,*)

    if(BSE) call ufBSE(nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_MO,eHF,eG0W0)

  end if

!------------------------------------------------------------------------
! Perform ufGW calculatiom
!------------------------------------------------------------------------

  if(doufGW) then
    
    call cpu_time(start_GW)
    call ufGW(nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_MO,eHF)
!   call CCGW(maxSCF_CC,thresh_CC,nBas,nC,nO,nV,nR,ERI_MO,ENuc,ERHF,eHF)
    call cpu_time(end_GW)
  
    t_GW = end_GW - start_GW
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for ufGW = ',t_GW,' seconds'
    write(*,*)

    if(BSE) call ufBSE(nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_MO,eHF,eG0W0)

  end if

!------------------------------------------------------------------------
! Perform G0T0pp calculatiom
!------------------------------------------------------------------------

  eG0T0(:,:) = eHF(:,:)

  if(doG0T0pp) then
    
    call cpu_time(start_GT)

    if(unrestricted) then 

      !print*,'!!! G0T0 NYI at the unrestricted level !!!'
       call UG0T0(doACFDT,exchange_kernel,doXBS,BSE,TDA_T,TDA,dBSE,dTDA,evDyn, &
                 spin_conserved,spin_flip,linGT,eta_GT,regGT,nBas,nC,nO,nV, &
                 nR,nS,ENuc,EUHF,ERI_AO,ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb, &
                 dipole_int_aa,dipole_int_bb,PHF,cHF,eHF,Vxc,eG0T0)

    else

!     call soG0T0(eta_GT,nBas,nC,nO,nV,nR,ENuc,ERHF,ERI_MO,eHF)
      call G0T0pp(doACFDT,exchange_kernel,doXBS,BSE,TDA_T,TDA,dBSE,dTDA,evDyn,ppBSE,singlet,triplet, &
                  linGT,eta_GT,regGT,nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_AO,ERI_MO,dipole_int_MO,      &  
                  PHF,cHF,eHF,Vxc,eG0T0)

    end if

    call cpu_time(end_GT)
  
    t_GT = end_GT - start_GT
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for G0T0 = ',t_GT,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform evGTpp calculatiom
!------------------------------------------------------------------------

  if(doevGTpp) then
    
    call cpu_time(start_GT)

    if(unrestricted) then

      call evUGT(maxSCF_GT,thresh_GT,n_diis_GT,doACFDT,exchange_kernel,doXBS, &
                 BSE,TDA_T,TDA,dBSE,dTDA,evDyn,spin_conserved,spin_flip,&
                 eta_GT,regGT,nBas,nC,nO,nV,nR,nS,ENuc,EUHF,ERI_AO, &
                 ERI_MO_aaaa,ERI_MO_aabb,ERI_MO_bbbb,dipole_int_aa, &
                 dipole_int_bb,PHF,cHF,eHF,Vxc,eG0T0)

    else

      call evGTpp(maxSCF_GT,thresh_GT,n_diis_GT,doACFDT,exchange_kernel,doXBS, &
                  BSE,TDA_T,TDA,dBSE,dTDA,evDyn,singlet,triplet,eta_GT,regGT,  & 
                  nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_AO,ERI_MO,dipole_int_MO,   &
                  PHF,cHF,eHF,Vxc,eG0T0)

    end if

    call cpu_time(end_GT)
  
    t_GT = end_GT - start_GT
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for evGT = ',t_GT,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform qsGTpp calculation
!------------------------------------------------------------------------

  if(doqsGTpp) then 

    call cpu_time(start_GT)

    if(unrestricted) then

      call qsUGT(maxSCF_GT,thresh_GT,n_diis_GT,doACFDT,exchange_kernel,doXBS,BSE,TDA_T, &
                 TDA,dBSE,dTDA,evDyn,spin_conserved,spin_flip,eta_GT,regGT,nBas,nC,nO,nV,&
                 nR,nS,nNuc,ZNuc,rNuc,ENuc,EUHF,S,X,T,V,Hc,ERI_AO,ERI_MO_aaaa,ERI_MO_aabb,&
                 ERI_MO_bbbb,dipole_int_AO,dipole_int_aa,dipole_int_bb,PHF,cHF,eHF) 
    else

      call qsGTpp(maxSCF_GT,thresh_GT,n_diis_GT,doACFDT,exchange_kernel,doXBS, &
                  BSE,TDA_T,TDA,dBSE,dTDA,evDyn,singlet,triplet,eta_GT,regGT,  &
                  nNuc,ZNuc,rNuc,ENuc,nBas,nC,nO,nV,nR,nS,ERHF,S,X,T,V,Hc,     & 
                  ERI_AO,ERI_MO,dipole_int_AO,dipole_int_MO,PHF,cHF,eHF)

    end if

    call cpu_time(end_GT)

    t_GT = end_GT - start_GT
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for qsGT = ',t_GT,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform G0T0eh calculatiom
!------------------------------------------------------------------------

  eG0T0(:,:) = eHF(:,:)

  if(doG0T0eh) then
    
    call cpu_time(start_GT)

    if(unrestricted) then 

      print*,'!!! eh G0T0 NYI at the unrestricted level !!!'

    else

      call G0T0eh(doACFDT,exchange_kernel,doXBS,BSE,BSE2,TDA_W,TDA,dBSE,dTDA,evDyn,ppBSE,singlet,triplet, &
                  linGW,eta_GW,regGW,nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_AO,ERI_MO,dipole_int_MO,PHF,cHF,eHF,Vxc,eG0T0)

    end if

    call cpu_time(end_GT)
  
    t_GT = end_GT - start_GT
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for G0T0 = ',t_GT,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform evGTeh calculation
!------------------------------------------------------------------------

  if(doevGTeh) then

    call cpu_time(start_GT)
    if(unrestricted) then 

    else

      call evGTeh(maxSCF_GT,thresh_GT,n_diis_GT,doACFDT,exchange_kernel,doXBS,                 &
                  BSE,BSE2,TDA_T,TDA,dBSE,dTDA,evDyn,ppBSE,singlet,triplet,linGT,eta_GT,regGT, &
                  nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI_AO,ERI_MO,dipole_int_MO,PHF,cHF,eHF,Vxc,eG0T0)
    end if
    call cpu_time(end_GT)

    t_GT = end_GT - start_GT
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for evGT = ',t_GT,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Perform qsGTeh calculation
!------------------------------------------------------------------------

  if(doqsGTeh) then 

    call wall_time(start_GT)

    if(unrestricted) then 
    
    else
 
      call qsGTeh(maxSCF_GT,thresh_GT,n_diis_GT,doACFDT,exchange_kernel,doXBS,                      &
                  BSE,BSE2,TDA_T,TDA,dBSE,dTDA,evDyn,singlet,triplet,eta_GT,regGT,nNuc,ZNuc,rNuc,ENuc, & 
                  nBas,nC,nO,nV,nR,nS,ERHF,S,X,T,V,Hc,ERI_AO,ERI_MO,dipole_int_AO,dipole_int_MO,PHF,cHF,eHF)

    end if

    call wall_time(end_GT)

    t_GT = end_GT - start_GT
    write(*,'(A65,1X,F9.3,A8)') 'Total wall time for qsGW = ',t_GT,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! Compute FCI 
!------------------------------------------------------------------------

  if(doFCI) then

    call cpu_time(start_CI)
    write(*,*) ' FCI is not yet implemented! Sorry.'
!   call FCI(nBas,nC,nO,nV,nR,ERI_MO,eHF)
    call cpu_time(end_CI)

    t_CI = end_CI - start_CI
    write(*,'(A65,1X,F9.3,A8)') 'Total CPU time for FCI = ',t_CI,' seconds'
    write(*,*)

  end if

!------------------------------------------------------------------------
! End of QuAcK
!------------------------------------------------------------------------

  call wall_time(end_QuAcK)

  t_QuAcK = end_QuAcK - start_QuAcK
  write(*,'(A65,1X,F9.3,A8)') 'Total wall time for QuAcK = ',t_QuAcK,' seconds'
  write(*,*)

end program QuAcK