subroutine RGIC_lda_exchange_individual_energy(nEns,wEns,nGrid,weight,rhow,rho,Ex)

! Compute the restricted version of the GIC exchange functional

  implicit none
  include 'parameters.h'

! Input variables

  integer,intent(in)            :: nEns
  double precision,intent(in)   :: wEns(nEns)
  integer,intent(in)            :: nGrid
  double precision,intent(in)   :: weight(nGrid)
  double precision,intent(in)   :: rhow(nGrid)
  double precision,intent(in)   :: rho(nGrid)

! Local variables

  integer                       :: iG
  double precision              :: CxGIC
  double precision              :: r,rI
  double precision              :: e_p,dedr

  double precision              :: a,b,c,w

! Output variables

  double precision,intent(out)  :: Ex

! Weight-dependent Cx coefficient for RMFL20 exchange functional


! Parameters for H2 at equilibrium

! a = + 0.5751782560799208d0
! b = - 0.021108186591137282d0
! c = - 0.36718902716347124d0

! Parameters for stretch H2

! a = + 0.01922622507087411d0
! b = - 0.01799647558018601d0
! c = - 0.022945430666782573d0

! Parameters for He

! a = 1.9125735895875828d0
! b = 2.715266992840757d0
! c = 2.1634223380633086d0


! Parameters for HNO

  a = 0.0061158387543040335d0
  b = -0.00005968703047293955d0
  c = -0.00001692245714408755d0

  w = wEns(2)
  CxGIC = 1d0 - w*(1d0 - w)*(a + b*(w - 0.5d0) + c*(w - 0.5d0)**2)
  CxGIC = CxLDA*CxGIC
 
! Compute LDA exchange matrix in the AO basis

  Ex = 0d0
  do iG=1,nGrid

    r  = max(0d0,rhow(iG))
    rI = max(0d0,rho(iG))

    if(r > threshold .and. rI > threshold) then

      e_p  =         CxGIC*r**(1d0/3d0)
      dedr = 1d0/3d0*CxGIC*r**(-2d0/3d0)
      Ex = Ex + weight(iG)*(e_p*rI + dedr*r*rI - dedr*r*r)

    endif

  enddo

end subroutine RGIC_lda_exchange_individual_energy