subroutine ppRPA(singlet_manifold,triplet_manifold,nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI,e)

! Perform pp-RPA calculation

  implicit none
  include 'parameters.h'

! Input variables

  logical,intent(in)            :: singlet_manifold
  logical,intent(in)            :: triplet_manifold
  integer,intent(in)            :: nBas
  integer,intent(in)            :: nC
  integer,intent(in)            :: nO
  integer,intent(in)            :: nV
  integer,intent(in)            :: nR
  integer,intent(in)            :: nS
  double precision,intent(in)   :: ENuc
  double precision,intent(in)   :: ERHF
  double precision,intent(in)   :: e(nBas)
  double precision,intent(in)   :: ERI(nBas,nBas,nBas,nBas)

! Local variables

  logical                       :: dRPA
  logical                       :: TDA
  logical                       :: BSE
  integer                       :: ispin
  double precision,allocatable  :: Omega(:,:)
  double precision,allocatable  :: XpY(:,:,:)

  double precision              :: rho
  double precision              :: Ec_ppRPA(nspin)

! Hello world

  write(*,*)
  write(*,*)'****************************************'
  write(*,*)'|  particle-particle RPA calculation   |'
  write(*,*)'****************************************'
  write(*,*)

! Initialization

  Ec_ppRPA(:) = 0d0

! Switch on exchange for TDHF

  dRPA = .false.
 
! Switch off Tamm-Dancoff approximation for TDHF

  TDA = .false.
 
! Switch off Bethe-Salpeter equation for TDHF

  BSE = .false. 

! Memory allocation

  allocate(Omega(nS,nspin),XpY(nS,nS,nspin))

! Singlet manifold

  if(singlet_manifold) then 

    ispin = 1

    call linear_response_pp(ispin,dRPA,TDA,BSE,nBas,nC,nO,nV,nR,nS,e,ERI,rho, & 
                            Ec_ppRPA)
!   call print_excitation('pp-RPA ',ispin,nS,Omega(:,ispin))

  endif

! Triplet manifold 

  if(triplet_manifold) then 

    ispin = 2

    call linear_response_pp(ispin,dRPA,TDA,BSE,nBas,nC,nO,nV,nR,nS,e,ERI,rho, &
                            Ec_ppRPA)
!   call print_excitation('pp-RPA ',ispin,nS,Omega(:,ispin))

  endif

  write(*,*)
  write(*,*)'-------------------------------------------------------------------------------'
  write(*,'(2X,A40,F15.6)') 'pp-RPA   correlation energy (singlet) =',Ec_ppRPA(1)
  write(*,'(2X,A40,F15.6)') 'pp-RPA   correlation energy (triplet) =',Ec_ppRPA(2)
  write(*,'(2X,A40,F15.6)') 'pp-RPA   correlation energy           =',Ec_ppRPA(1) + Ec_ppRPA(2)
  write(*,'(2X,A40,F15.6)') 'pp-RPA   total energy                 =',ENuc + ERHF + Ec_ppRPA(1) + Ec_ppRPA(2)
  write(*,*)'-------------------------------------------------------------------------------'
  write(*,*)

end subroutine ppRPA