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https://github.com/pfloos/quack
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63 lines
1.6 KiB
Fortran
63 lines
1.6 KiB
Fortran
subroutine elda_correlation_Levy_Zahariev_shift(nEns,aLF,nGrid,weight,rho,EcLZ)
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! Compute Levy-Zahariev LDA correlation shift of 2-glomium for various states
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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) :: aLF(nEns)
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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) :: rho(nGrid,nspin)
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! Local variables
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integer :: iG
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double precision :: ra,rb,r,ec_p
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double precision :: dFcdra,dFcdrb
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! Output variables
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double precision,intent(out) :: EcLZ
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! Compute Levy-Zahariev eLDA correlation shift
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EcLZ = 0d0
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do iG=1,nGrid
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ra = max(0d0,rho(iG,1))
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rb = max(0d0,rho(iG,2))
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r = ra + rb
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if(ra > threshold) then
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ec_p = aLF(1)/(1d0 + aLF(2)*r**(-1d0/6d0) + aLF(3)*r**(-1d0/3d0))
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dFcdra = aLF(2)*r**(-1d0/6d0) + 2d0*aLF(3)*r**(-1d0/3d0)
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dFcdra = dFcdra/(1d0 + aLF(2)*r**(-1d0/6d0) + aLF(3)*r**(-1d0/3d0))
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dFcdra = ec_p*dFcdra/6d0
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dFcdra = ec_p + dFcdra
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EcLZ = EcLZ - weight(iG)*r*r*dFcdra
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end if
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if(rb > threshold) then
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ec_p = aLF(1)/(1d0 + aLF(2)*r**(-1d0/6d0) + aLF(3)*r**(-1d0/3d0))
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dFcdrb = aLF(2)*r**(-1d0/6d0) + 2d0*aLF(3)*r**(-1d0/3d0)
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dFcdrb = dFcdrb/(1d0 + aLF(2)*r**(-1d0/6d0) + aLF(3)*r**(-1d0/3d0))
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dFcdrb = ec_p*dFcdrb/6d0
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dFcdrb = ec_p + dFcdrb
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EcLZ = EcLZ - weight(iG)*r*r*dFcdrb
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end if
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end do
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end subroutine elda_correlation_Levy_Zahariev_shift
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