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QuAcK/src/eDFT/UCC_lda_exchange_potential.f90

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subroutine UCC_lda_exchange_potential(nEns,wEns,nCC,aCC,nGrid,weight,nBas,AO,rho,Cx_choice,doNcentered,Fx)
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! Compute the unrestricted version of the curvature-corrected exchange potential
implicit none
include 'parameters.h'
! Input variables
integer,intent(in) :: nEns
double precision,intent(in) :: wEns(nEns)
integer,intent(in) :: nCC
double precision,intent(in) :: aCC(nCC,nEns-1)
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integer,intent(in) :: nGrid
double precision,intent(in) :: weight(nGrid)
integer,intent(in) :: nBas
double precision,intent(in) :: AO(nBas,nGrid)
double precision,intent(in) :: rho(nGrid)
integer,intent(in) :: Cx_choice
logical,intent(in) :: doNcentered
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! Local variables
integer :: mu,nu,iG
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double precision :: r,vAO
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double precision :: a1,b1,c1,d1,w1
double precision :: a2,b2,c2,d2,w2
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double precision :: Fx1,Fx2,Cx
! Output variables
double precision,intent(out) :: Fx(nBas,nBas)
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! Defining enhancements factor for weight-dependent functionals
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if(doNcentered) then
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! Parameters for first state
a1 = aCC(1,1)
b1 = aCC(2,1)
c1 = aCC(3,1)
d1 = aCC(4,1)
! Parameters for second state
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a2 = aCC(1,2)
b2 = aCC(2,2)
c2 = aCC(3,2)
d2 = aCC(4,2)
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w1 = wEns(2)
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Fx1 = 1d0 + a1*w1 + b1*w1**2 + c1*w1**3 + d1*w1**4
w2 = wEns(3)
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Fx2 = 1d0 + a2*w2 + b2*w2**2 + c2*w2**3 + d2*w2**4
else
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! Parameters for first state
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a1 = aCC(1,1)
b1 = aCC(2,1)
c1 = aCC(3,1)
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! Parameters for second state
a2 = aCC(1,2)
b2 = aCC(2,2)
c2 = aCC(3,2)
w1 = wEns(2)
Fx1 = 1d0 - w1*(1d0 - w1)*(a1 + b1*(w1 - 0.5d0) + c1*(w1 - 0.5d0)**2)
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w2 = wEns(3)
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Fx2 = 1d0 - w2*(1d0 - w2)*(a2 + b2*(w2 - 0.5d0) + c2*(w2 - 0.5d0)**2)
endif
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select case (Cx_choice)
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case(1)
Cx = CxLSDA*Fx1
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case(2)
Cx = CxLSDA*Fx2
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case(3)
Cx = CxLSDA*Fx2*Fx1
case default
Cx = CxLSDA
end select
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! Compute LDA exchange matrix in the AO basis
Fx(:,:) = 0d0
do mu=1,nBas
do nu=1,nBas
do iG=1,nGrid
r = max(0d0,rho(iG))
if(r > threshold) then
vAO = weight(iG)*AO(mu,iG)*AO(nu,iG)
Fx(mu,nu) = Fx(mu,nu) + vAO*4d0/3d0*Cx*r**(1d0/3d0)
endif
enddo
enddo
enddo
end subroutine UCC_lda_exchange_potential