2019-03-13 11:07:31 +01:00
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subroutine exchange_energy(rung,DFA,nEns,wEns,nGrid,weight,nBas,P,FxHF,rho,drho,Ex)
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! Compute the exchange energy
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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) :: rung
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character(len=12),intent(in) :: DFA
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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) :: 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) :: P(nBas,nBas)
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double precision,intent(in) :: FxHF(nBas,nBas)
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double precision,intent(in) :: rho(nGrid)
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2020-03-14 23:00:44 +01:00
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double precision,intent(in) :: drho(ncart,nGrid)
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2019-03-13 11:07:31 +01:00
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! Local variables
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double precision :: ExLDA,ExGGA,ExHF
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double precision :: cX,aX,aC
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! Output variables
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double precision,intent(out) :: Ex
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select case (rung)
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! Hartree calculation
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case(0)
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Ex = 0d0
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! LDA functionals
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case(1)
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call lda_exchange_energy(DFA,nEns,wEns,nGrid,weight,rho,ExLDA)
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Ex = ExLDA
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! GGA functionals
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case(2)
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call gga_exchange_energy(DFA,nEns,wEns,nGrid,weight,rho,drho,ExGGA)
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Ex = ExGGA
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! Hybrid functionals
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case(4)
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cX = 0.20d0
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aX = 0.72d0
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aC = 0.81d0
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call lda_exchange_energy(DFA,nEns,wEns,nGrid,weight,rho,ExLDA)
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call gga_exchange_energy(DFA,nEns,wEns,nGrid,weight,rho,drho,ExGGA)
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call fock_exchange_energy(nBas,P,FxHF,ExHF)
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Ex = ExLDA &
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+ cX*(ExHF - ExLDA) &
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+ aX*(ExGGA - ExLDA)
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! Hartree-Fock calculation
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2020-03-15 14:33:53 +01:00
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2019-03-13 11:07:31 +01:00
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case(666)
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call fock_exchange_energy(nBas,P,FxHF,ExHF)
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Ex = ExHF
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end select
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end subroutine exchange_energy
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