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https://github.com/pfloos/quack
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48 lines
1.1 KiB
Fortran
48 lines
1.1 KiB
Fortran
subroutine huckel_guess(nBas,nO,S,Hc,ERI,X,cp,F,Fp,e,c)
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! Hickel guess of the molecular orbitals for HF calculation
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implicit none
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! Input variables
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integer,intent(in) :: nBas
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integer,intent(in) :: nO
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double precision,intent(in) :: S(nBas,nBas)
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double precision,intent(in) :: Hc(nBas,nBas)
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double precision,intent(in) :: ERI(nBas,nBas,nBas,nBas)
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double precision,intent(in) :: X(nBas,nBas)
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double precision,intent(inout):: cp(nBas,nBas)
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double precision,intent(inout):: F(nBas,nBas)
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double precision,intent(inout):: Fp(nBas,nBas)
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double precision,intent(inout):: e(nBas)
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! Local variables
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integer :: mu,nu
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double precision :: a
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! Output variables
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double precision,intent(out) :: c(nBas,nBas)
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a = 1.75d0
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F(:,:) = Hc(:,:)
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do mu=1,nBas
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do nu=mu+1,nBas
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F(mu,nu) = 0.5d0*a*S(mu,nu)*(Hc(mu,mu) + Hc(nu,nu))
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F(nu,mu) = F(mu,nu)
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enddo
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enddo
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Fp(:,:) = matmul(transpose(X(:,:)),matmul(F(:,:),X(:,:)))
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cp(:,:) = Fp(:,:)
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call diagonalize_matrix(nBas,cp,e)
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c(:,:) = matmul(X(:,:),cp(:,:))
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end subroutine
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