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https://github.com/pfloos/quack
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149 lines
2.8 KiB
Fortran
149 lines
2.8 KiB
Fortran
subroutine UCC_lda_exchange_individual_energy(nEns,wEns,nCC,aCC,nGrid,weight,rhow,rho,Cx_choice,doNcentered,kappa,Ex)
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! Compute the unrestricted version of the curvature-corrected exchange functional
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implicit none
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include 'parameters.h'
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! Input variables
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integer,intent(in) :: nEns
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double precision,intent(in) :: wEns(nEns)
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integer,intent(in) :: nCC
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double precision,intent(in) :: aCC(nCC,nEns-1)
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integer,intent(in) :: nGrid
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double precision,intent(in) :: weight(nGrid)
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double precision,intent(in) :: rhow(nGrid)
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double precision,intent(in) :: rho(nGrid)
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integer,intent(in) :: Cx_choice
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logical,intent(in) :: doNcentered
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double precision,intent(in) :: kappa
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! Local variables
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integer :: iG
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double precision :: r,rI
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double precision :: e_p,dedr
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double precision :: Exrr,ExrI,ExrrI
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double precision :: a1,b1,c1,d1,w1
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double precision :: a2,b2,c2,d2,w2
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double precision :: Fx1,Fx2,Cx
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! Output variables
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double precision,intent(out) :: Ex
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! External variable
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double precision,external :: electron_number
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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
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a1 = aCC(1,1)
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b1 = aCC(2,1)
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c1 = aCC(3,1)
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d1 = aCC(4,1)
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! Parameters for second state
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a2 = aCC(1,2)
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b2 = aCC(2,2)
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c2 = aCC(3,2)
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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
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w2 = wEns(3)
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Fx2 = 1d0 + a2*w2 + b2*w2**2 + c2*w2**3 + d2*w2**4
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else
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! Parameters for first state
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a1 = aCC(1,1)
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b1 = aCC(2,1)
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c1 = aCC(3,1)
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! Parameters for second state
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a2 = aCC(1,2)
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b2 = aCC(2,2)
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c2 = aCC(3,2)
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w1 = wEns(2)
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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)
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endif
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select case (Cx_choice)
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case(1)
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Cx = CxLSDA*Fx1
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case(2)
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Cx = CxLSDA*Fx2
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case(3)
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Cx = CxLSDA*Fx2*Fx1
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case default
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Cx = CxLSDA
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end select
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! Compute LDA exchange matrix in the AO basis
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Ex = 0d0
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Exrr = 0d0
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ExrI = 0d0
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ExrrI = 0d0
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do iG=1,nGrid
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r = max(0d0,rhow(iG))
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rI = max(0d0,rho(iG))
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if(r > threshold) then
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e_p = Cx*r**(1d0/3d0)
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dedr = 1d0/3d0*Cx*r**(-2d0/3d0)
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Exrr = Exrr - weight(iG)*dedr*r*r
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if(rI > threshold) then
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ExrI = ExrI + weight(iG)*e_p*rI
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ExrrI = ExrrI + weight(iG)*dedr*r*rI
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endif
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endif
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enddo
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! De-scaling for N-centered ensemble
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if(doNcentered) then
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Exrr = kappa*Exrr
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ExrI = kappa*ExrI
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endif
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Ex = Exrr + ExrI + ExrrI
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end subroutine UCC_lda_exchange_individual_energy
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