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73 lines
1.9 KiB
Fortran
73 lines
1.9 KiB
Fortran
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! State average energy
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! Calculation of the state average energy from the integrals and the
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! density matrices.
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! \begin{align*}
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! E = \sum_{ij} h_{ij} \gamma_{ij} + \frac{1}{2} v_{ij}^{kl} \Gamma_{ij}^{kl}
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! \end{align*}
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! $h_{ij}$: mono-electronic integral
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! $\gamma_{ij}$: one electron density matrix
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! $v_{ij}^{kl}$: bi-electronic integral
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! $\Gamma_{ij}^{kl}$: two electrons density matrix
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! TODO: OMP version
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! PROVIDED:
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! | mo_one_e_integrals | double precision | mono-electronic integrals |
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! | get_two_e_integral | double precision | bi-electronic integrals |
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! | one_e_dm_mo | double precision | one electron density matrix |
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! | two_e_dm_mo | double precision | two electrons density matrix |
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! | nuclear_repulsion | double precision | nuclear repulsion |
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! | mo_num | integer | number of MOs |
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! Output:
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! | energy | double precision | state average energy |
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! Internal:
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! | mono_e | double precision | mono-electronic energy |
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! | bi_e | double precision | bi-electronic energy |
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! | i,j,k,l | integer | indexes to loop over the MOs |
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subroutine state_average_energy(energy)
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implicit none
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double precision, intent(out) :: energy
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double precision :: get_two_e_integral
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double precision :: mono_e, bi_e
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integer :: i,j,k,l
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! mono electronic part
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mono_e = 0d0
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do j = 1, mo_num
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do i = 1, mo_num
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mono_e = mono_e + mo_one_e_integrals(i,j) * one_e_dm_mo(i,j)
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enddo
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enddo
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! bi electronic part
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bi_e = 0d0
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do l = 1, mo_num
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do k = 1, mo_num
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do j = 1, mo_num
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do i = 1, mo_num
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bi_e = bi_e + get_two_e_integral(i,j,k,l,mo_integrals_map) * two_e_dm_mo(i,j,k,l)
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enddo
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enddo
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enddo
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enddo
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! State average energy
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energy = mono_e + 0.5d0 * bi_e + nuclear_repulsion
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! Check
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!call print_energy_components
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print*,'State average energy:', energy
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!print*,ci_energy
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end
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