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https://github.com/pfloos/quack
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58 lines
1.3 KiB
Fortran
58 lines
1.3 KiB
Fortran
subroutine elda_correlation_individual_energy(aLF,nGrid,weight,rhow,rho,Ec)
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! Compute LDA correlation individual energy 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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double precision,intent(in) :: aLF(3)
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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,nspin)
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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
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double precision :: raI,rbI,rI
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double precision :: ec_p,dFcdr
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! Output variables
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double precision,intent(out) :: Ec(nsp)
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! Compute eLDA correlation potential
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Ec(:) = 0d0
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do iG=1,nGrid
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ra = max(0d0,rhow(iG,1))
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rb = max(0d0,rhow(iG,2))
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raI = max(0d0,rho(iG,1))
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rbI = max(0d0,rho(iG,2))
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r = ra + rb
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rI = raI + rbI
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if(r > threshold .or. rI > 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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dFcdr = aLF(2)*r**(-1d0/6d0) + 2d0*aLF(3)*r**(-1d0/3d0)
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dFcdr = dFcdr/(1d0 + aLF(2)*r**(-1d0/6d0) + aLF(3)*r**(-1d0/3d0))
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dFcdr = ec_p*dFcdr/(6d0*r)
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dFcdr = ec_p + dFcdr*r
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Ec(2) = Ec(2) + weight(iG)*rI*dFcdr
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end if
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end do
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end subroutine elda_correlation_individual_energy
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