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41 lines
741 B
Fortran
41 lines
741 B
Fortran
BEGIN_PROVIDER [ double precision, EcCCSD ]
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implicit none
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BEGIN_DOC
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! CCSD correlation energy in non-canonical form
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END_DOC
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! Local variables
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integer :: i,j,a,b
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EcCCSD = 0d0
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! Singles contribution
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do i=1,spin_occ_num
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do a=1,spin_vir_num
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EcCCSD = EcCCSD + spin_fock_matrix_mo_ov(i,a)*t1_cc(i,a)
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end do
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end do
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! Doubles contribution
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do i=1,spin_occ_num
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do j=1,spin_occ_num
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do a=1,spin_vir_num
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do b=1,spin_vir_num
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EcCCSD = EcCCSD &
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+ 0.5d0*OOVV(i,j,a,b)*t1_cc(i,a)*t1_cc(j,b) &
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+ 0.25d0*OOVV(i,j,a,b)*t2_cc(i,j,a,b)
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end do
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end do
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end do
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end do
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END_PROVIDER
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