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https://github.com/LCPQ/quantum_package
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73 lines
2.7 KiB
Fortran
73 lines
2.7 KiB
Fortran
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subroutine pt2_delta_rho_one_point(det_pert,c_pert,e_2_pert,H_pert_diag,Nint,ndet,n_st)
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use bitmasks
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implicit none
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integer, intent(in) :: Nint,ndet,n_st
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integer(bit_kind), intent(in) :: det_pert(Nint,2)
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double precision , intent(out) :: c_pert(n_st),e_2_pert(n_st),H_pert_diag(N_st)
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double precision :: i_O1_psi_array(N_st)
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double precision :: i_H_psi_array(N_st)
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BEGIN_DOC
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! compute the perturbatibe contribution to the Integrated Spin density at z = z_one point of one determinant
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!
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! for the various n_st states, at various level of theory.
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!
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! c_pert(i) = <psi(i)|H|det_pert>/(<psi(i)|H|psi(i)> - <det_pert|H|det_pert>)
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!
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! e_2_pert(i) = c_pert(i) * <det_pert|O|psi(i)>
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!
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! H_pert_diag(i) = c_pert(i)^2 * <det_pert|O|det_pert>
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!
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! To get the contribution of the first order :
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!
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! <O_1> = sum(over i) e_2_pert(i)
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!
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! To get the contribution of the diagonal elements of the second order :
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!
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! [ <O_0> + <O_1> + sum(over i) H_pert_diag(i) ] / [1. + sum(over i) c_pert(i) **2]
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!
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END_DOC
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integer :: i,j
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double precision :: diag_H_mat_elem,diag_o1_mat_elem_alpha_beta
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integer :: exc(0:2,2,2)
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integer :: degree
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double precision :: phase,delta_e,h,oii,diag_o1_mat_elem
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integer :: h1,h2,p1,p2,s1,s2
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ASSERT (Nint == N_int)
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ASSERT (Nint > 0)
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! call get_excitation_degree(HF_bitmask,det_pert,degree,N_int)
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! if(degree.gt.degree_max_generators+1)then
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! H_pert_diag = 0.d0
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! e_2_pert = 0.d0
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! c_pert = 0.d0
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! return
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! endif
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call i_O1_psi_alpha_beta(mo_integrated_delta_rho_one_point,det_pert,psi_selectors,psi_selectors_coef,Nint,N_det_selectors,psi_selectors_size,N_st,i_O1_psi_array)
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call i_H_psi(det_pert,psi_selectors,psi_selectors_coef,Nint,N_det_selectors,psi_selectors_size,N_st,i_H_psi_array)
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h = diag_H_mat_elem(det_pert,Nint)
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oii = diag_O1_mat_elem_alpha_beta(mo_integrated_delta_rho_one_point,det_pert,N_int)
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do i =1,N_st
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if(CI_electronic_energy(i)>h.and.CI_electronic_energy(i).ne.0.d0)then
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c_pert(i) = -1.d0
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e_2_pert(i) = selection_criterion*selection_criterion_factor*2.d0
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else if (dabs(CI_electronic_energy(i) - h) > 1.d-6) then
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c_pert(i) = i_H_psi_array(i) / (CI_electronic_energy(i) - h)
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e_2_pert(i) = c_pert(i) * (i_O1_psi_array(i)+i_O1_psi_array(i) ) + c_pert(i) * c_pert(i) * oii
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H_pert_diag(i) = c_pert(i) * (i_O1_psi_array(i)+i_O1_psi_array(i) )
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else
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c_pert(i) = -1.d0
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e_2_pert(i) = -dabs(i_H_psi_array(i))
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H_pert_diag(i) = c_pert(i) * i_O1_psi_array(i)
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endif
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enddo
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end
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