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https://github.com/pfloos/quack
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126 lines
3.2 KiB
Fortran
126 lines
3.2 KiB
Fortran
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subroutine CC_B88_gga_exchange_potential(nEns,wEns,nCC,aCC,nGrid,weight,nBas,&
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AO,dAO,rho,drho,Cx_choice,doNcentered,Fx)
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! Compute the unrestricted version of the curvature-corrected exchange potential
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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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integer,intent(in) :: nBas
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double precision,intent(in) :: AO(nBas,nGrid)
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double precision,intent(in) :: dAO(3,nBas,nGrid)
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double precision,intent(in) :: rho(nGrid)
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double precision,intent(in) :: drho(3,nGrid)
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integer,intent(in) :: Cx_choice
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logical,intent(in) :: doNcentered
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! Local variables
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integer :: mu,nu,iG
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double precision :: b
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double precision :: vAO,gAO
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double precision :: r,g,x,dxdr,dxdg,f
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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) :: Fx(nBas,nBas)
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! Coefficients for B88 GGA exchange functional
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b = 0.0042d0
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! Defining enhancements factor for weight-dependent functionals
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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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select case (Cx_choice)
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case(1)
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Cx = Fx1
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case(2)
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Cx = Fx2
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case(3)
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Cx = Fx2*Fx1
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case default
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Cx = 1.d0
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end select
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! Compute GGA exchange matrix in the AO basis
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Fx(:,:) = 0d0
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do mu=1,nBas
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do nu=1,nBas
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do iG=1,nGrid
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r = max(0d0,rho(iG))
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if(r > threshold) then
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vAO = weight(iG)*AO(mu,iG)*AO(nu,iG)
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g = drho(1,iG)**2 + drho(2,iG)**2 + drho(3,iG)**2
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x = sqrt(g)/r**(4d0/3d0)
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dxdr = - 4d0*sqrt(g)/(3d0*r**(7d0/3d0))/x
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dxdg = + 1d0/(2d0*sqrt(g)*r**(4d0/3d0))/x
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f = b*x**2/(1d0 + 6d0*b*x*asinh(x))
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Fx(mu,nu) = Fx(mu,nu) + vAO*( &
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4d0/3d0*r**(1d0/3d0)*(CxLSDA - f) &
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- 2d0*r**(4d0/3d0)*dxdr*f &
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+ r**(4d0/3d0)*dxdr*(6d0*b*x*asinh(x) + 6d0*b*x**2/sqrt(1d0+x**2))*f/(1d0 + 6d0*b*x*asinh(x)) )
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gAO = drho(1,iG)*(dAO(1,mu,iG)*AO(nu,iG) + AO(mu,iG)*dAO(1,nu,iG)) &
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+ drho(2,iG)*(dAO(2,mu,iG)*AO(nu,iG) + AO(mu,iG)*dAO(2,nu,iG)) &
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+ drho(3,iG)*(dAO(3,mu,iG)*AO(nu,iG) + AO(mu,iG)*dAO(3,nu,iG))
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gAO = weight(iG)*gAO
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Fx(mu,nu) = Fx(mu,nu) + 2d0*gAO*r**(4d0/3d0)*dxdg*( &
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- 2d0*f + (6d0*b*x*asinh(x) + 6d0*b*x**2/sqrt(1d0+x**2))*f/(1d0 + 6d0*b*x*asinh(x)) )
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end if
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end do
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end do
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end do
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Fx(:,:) = Cx*Fx(:,:)
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end subroutine CC_B88_gga_exchange_potential
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